Alright... so this gets a bit weirder, but the Google Analytics part of this looks separate, though it is still something I'd consider an issue. On that, it looks like after first loading into the desktop, Avast attempts to collect data (and ignoring any user-settings on the matter) to then send off for Google Analytics.
As for the popup, it looks to just be more of a random occurrence, more commonly appearing upon loading into the Desktop, which then made it look like the two events were related as they would appear at a similar time... though I suppose they could still be related in some form.
The popup can also occur just randomly after hours of a PC being on, here's a snippet from the AvastUI.log during such an instance:
[2020-09-21 19:27:57.823] [info ] [nl_client ] [ 8908: 8540] Reserve action - rejects request (id:'nag_limit').
[2020-09-21 19:28:57.854] [info ] [opm_client ] [ 8908:12536] Opm change event arrived, placement 'popup' count of message(s) '1'.
[2020-09-21 19:28:57.854] [info ] [opm_client ] [ 8908:12536] Show content for message id: 'AVAST_AV_CB_MIGRATION_SOFT_NAG'
[2020-09-21 19:28:57.855] [info ] [nl_client ] [ 8908:12536] Reserve action - rejects request (id:'nag_limit').
[2020-09-21 19:29:57.890] [info ] [opm_client ] [ 8908: 8540] Opm change event arrived, placement 'popup' count of message(s) '1'.
[2020-09-21 19:29:57.890] [info ] [opm_client ] [ 8908: 8540] Show content for message id: 'AVAST_AV_CB_MIGRATION_SOFT_NAG'
[2020-09-21 19:29:57.890] [info ] [nl_client ] [ 8908: 8540] Reserve action - acknowledge request (id:'nag_limit').
[2020-09-21 19:29:57.891] [info ] [ui_renderer] [ 8908: 8540] WindowManager::ShowStoreWindow
[2020-09-21 19:29:57.891] [info ] [opm_window ] [ 8908: 8540] Constructing of 'popup' (msg id: 'AVAST_AV_CB_MIGRATION_SOFT_NAG')' finished with result '1'.
[2020-09-21 19:29:58.122] [info ] [base_init ] [ 2156: 4352] Entering basInitLibrary...
[2020-09-21 19:29:58.122] [info ] [base_init ] [ 2156: 4352] Calling cmnbInit...
[2020-09-21 19:29:58.122] [info ] [base_init ] [ 2156: 4352] Calling CrashHandlerInstall...
[2020-09-21 19:29:58.124] [info ] [crashguard ] [ 2156: 4352] CrashGuard global exception handler installed
[2020-09-21 19:29:58.124] [info ] [crashguard ] [ 2156: 4352] CrashGuard initialized successfully, external dumping enabled
[2020-09-21 19:29:58.126] [notice ] [crashguard ] [ 2156: 7744] Process monitoring installed.
[2020-09-21 19:29:58.128] [info ] [settings ] [ 2156: 4352] paths.ini_store configuration is empty, settings ini store folder to asw::instup::GetDataDirectory.
[2020-09-21 19:29:58.144] [warning] [crashguard ] [ 2156: 4352] Installing crashguard from DLL instead of executable. Crashes in global destruction cannot be handled.
[2020-09-21 19:29:58.144] [info ] [crashguard ] [ 2156: 4352] Crash handler installed successfully process-wide from module 140735530205184h
[2020-09-21 19:29:58.144] [info ] [base_init ] [ 2156: 4352] Validating paths...
[2020-09-21 19:29:58.152] [info ] [base_init ] [ 2156: 4352] basReinitLanguage: language 1033 from 'C:\Program Files\Avast Software\Avast\1033' was successfully loaded.
[2020-09-21 19:29:58.152] [info ] [base_init ] [ 2156: 4352] Calling GetComputerName...
[2020-09-21 19:29:58.152] [info ] [base_init ] [ 2156: 4352] Leaving basInitLibrary...
[2020-09-21 19:29:58.156] [info ] [crashguard ] [ 2156: 4352] Crash handler is already resident in this process. Enabling only manual dumping from this binary.
[2020-09-21 19:29:58.156] [info ] [crashguard ] [ 2156: 4352] CrashGuard initialized successfully, external dumping enabled
[2020-09-21 19:29:58.157] [notice ] [UI:Rend:1 ] [ 2156: 4352] Av5_App::InitInstance() - START
[2020-09-21 19:29:58.157] [notice ] [UI:Rend:1 ] [ 2156: 4352] Parent processID:8908:0x000022cc UserSessionID:1
[2020-09-21 19:29:58.122] [info ] [base_init ] [ 5356:14420] Entering basInitLibrary...
[2020-09-21 19:29:58.122] [info ] [base_init ] [ 5356:14420] Calling cmnbInit...
[2020-09-21 19:29:58.122] [info ] [base_init ] [ 5356:14420] Calling CrashHandlerInstall...
[2020-09-21 19:29:58.124] [info ] [crashguard ] [ 5356:14420] CrashGuard global exception handler installed
[2020-09-21 19:29:58.124] [info ] [crashguard ] [ 5356:14420] CrashGuard initialized successfully, external dumping enabled
[2020-09-21 19:29:58.125] [notice ] [crashguard ] [ 5356: 2464] Process monitoring installed.
[2020-09-21 19:29:58.128] [info ] [settings ] [ 5356:14420] paths.ini_store configuration is empty, settings ini store folder to asw::instup::GetDataDirectory.
[2020-09-21 19:29:58.144] [warning] [crashguard ] [ 5356:14420] Installing crashguard from DLL instead of executable. Crashes in global destruction cannot be handled.
[2020-09-21 19:29:58.144] [info ] [crashguard ] [ 5356:14420] Crash handler installed successfully process-wide from module 140735530205184h
[2020-09-21 19:29:58.144] [info ] [base_init ] [ 5356:14420] Validating paths...
[2020-09-21 19:29:58.153] [info ] [base_init ] [ 5356:14420] basReinitLanguage: language 1033 from 'C:\Program Files\Avast Software\Avast\1033' was successfully loaded.
[2020-09-21 19:29:58.153] [info ] [base_init ] [ 5356:14420] Calling GetComputerName...
[2020-09-21 19:29:58.153] [info ] [base_init ] [ 5356:14420] Leaving basInitLibrary...
[2020-09-21 19:29:58.156] [info ] [crashguard ] [ 5356:14420] Crash handler is already resident in this process. Enabling only manual dumping from this binary.
[2020-09-21 19:29:58.156] [info ] [crashguard ] [ 5356:14420] CrashGuard initialized successfully, external dumping enabled
[2020-09-21 19:29:58.157] [notice ] [UI:Rend:1 ] [ 5356:14420] Av5_App::InitInstance() - START
[2020-09-21 19:29:58.157] [notice ] [UI:Rend:1 ] [ 5356:14420] Parent processID:8908:0x000022cc UserSessionID:1
[2020-09-21 19:29:58.166] [info ] [gui_cache ] [ 2156: 4352] Resource path set to: C:\Program Files\Avast Software\Avast\gui_resources\1.0.558\
[2020-09-21 19:29:58.166] [info ] [gui_cache ] [ 5356:14420] Resource path set to: C:\Program Files\Avast Software\Avast\gui_resources\1.0.558\
[2020-09-21 19:29:58.175] [info ] [ui_renderer] [ 2156: 4352] Create Renderer SUCCEED! Type: 2 Version: 1.1.0
[2020-09-21 19:29:58.175] [info ] [ui_renderer] [ 5356:14420] Create Renderer SUCCEED! Type: 2 Version: 1.1.0
[2020-09-21 19:29:58.198] [info ] [gui_cache ] [ 8908: 9040] Started getting content of current update file
[2020-09-21 19:29:58.198] [info ] [gui_cache ] [ 8908: 9040] Finished getting content of current update file
[2020-09-21 19:29:58.216] [notice ] [chromium ] [ 2156: 4352] CefRenderer::ExecuteCefProcess
[2020-09-21 19:29:58.217] [notice ] [chromium ] [ 5356:14420] CefRenderer::ExecuteCefProcess
[2020-09-21 19:29:58.232] [info ] [avsvcui ] [ 8908: 9056] {"guiLock":false,"issues":null,"lastScanTime":1599996392,"lastUpdateTime":1600696049,"licExpDays":137,"licType":"LicenseSubscription","lic_state":"lic_valid","mainStatus":"green","managed":false,"ncUnreadItemsCount":0,"numberOfDefs":14938361,"product":"premier","productEx":"","productSeller":"","silentMode":0}
[2020-09-21 19:29:58.235] [info ] [gui_cache ] [ 8908: 9056] Started getting content of current update file
[2020-09-21 19:29:58.236] [info ] [gui_cache ] [ 8908: 9056] Finished getting content of current update file
[2020-09-21 19:29:58.453] [warning] [chromium ] [ 8908: 632] CefDialog IPMResponseFailed with HttpStatus: 204 for url: https://ipm-provider.ff.avast.com/?data=[LONG BLOCK]&action=1&p_tbc=1&p_mid=AVAST_AV_CB_MIGRATION_SOFT_NAG&p_elm=2
[2020-09-21 19:29:58.454] [warning] [opm_control] [ 8908: 8896] Download content for message 'AVAST_AV_CB_MIGRATION_SOFT_NAG' (https://ipm-provider.ff.avast.com/?data=[LONG BLOCK]&action=1&p_tbc=1&p_mid=AVAST_AV_CB_MIGRATION_SOFT_NAG&p_elm=2) failed '204'.
[2020-09-21 19:29:58.454] [info ] [opm_client ] [ 8908: 8896] Call message shown 'AVAST_AV_CB_MIGRATION_SOFT_NAG'
[2020-09-21 19:29:58.528] [info ] [opm_client ] [ 8908: 9040] Opm change event arrived, placement 'popup' count of message(s) '1'.
[2020-09-21 19:29:58.528] [info ] [opm_client ] [ 8908: 9040] Show content for message id: 'AVAST_AV_CB_MIGRATION_SOFT_NAG'
[2020-09-21 19:29:58.529] [info ] [nl_client ] [ 8908: 9040] Reserve action - rejects request (id:'nag_limit').
and then also the OPM.log:
[2020-09-21 19:26:57.791] [info ] [opm ] [ 2400: 4496] Message repeat finished.
[2020-09-21 19:27:57.792] [info ] [opm ] [ 2400:14056] The message 'AVAST_AV_CB_MIGRATION_SOFT_NAG' is triggered.
[2020-09-21 19:27:57.792] [info ] [opm_svc ] [ 2400:14056] Selected message(s) (count: '1') with priority '2600', placement 'popup'.
[2020-09-21 19:27:57.823] [info ] [opm_svc ] [ 2400:14056] Send opm message refresh to client, placement 'popup'.
[2020-09-21 19:27:57.824] [info ] [opm ] [ 2400: 4496] Message repeat started (message 'AVAST_AV_CB_MIGRATION_SOFT_NAG', after: '60' sec).
[2020-09-21 19:27:57.824] [info ] [opm ] [ 2400: 4496] Message repeat finished.
[2020-09-21 19:28:57.826] [info ] [opm ] [ 2400: 8068] The message 'AVAST_AV_CB_MIGRATION_SOFT_NAG' is triggered.
[2020-09-21 19:28:57.826] [info ] [opm_svc ] [ 2400: 8068] Selected message(s) (count: '1') with priority '2600', placement 'popup'.
[2020-09-21 19:28:57.854] [info ] [opm_svc ] [ 2400: 8068] Send opm message refresh to client, placement 'popup'.
[2020-09-21 19:28:57.855] [info ] [opm ] [ 2400: 4496] Message repeat started (message 'AVAST_AV_CB_MIGRATION_SOFT_NAG', after: '60' sec).
[2020-09-21 19:28:57.855] [info ] [opm ] [ 2400: 4496] Message repeat finished.
[2020-09-21 19:29:57.856] [info ] [opm ] [ 2400:12764] The message 'AVAST_AV_CB_MIGRATION_SOFT_NAG' is triggered.
[2020-09-21 19:29:57.856] [info ] [opm_svc ] [ 2400:12764] Selected message(s) (count: '1') with priority '2600', placement 'popup'.
[2020-09-21 19:29:57.890] [info ] [opm_svc ] [ 2400:12764] Send opm message refresh to client, placement 'popup'.
[2020-09-21 19:29:57.891] [info ] [opm ] [ 2400: 4496] Message processed id 'AVAST_AV_CB_MIGRATION_SOFT_NAG'.
[2020-09-21 19:29:58.455] [info ] [opm ] [ 2400: 4496] Message shown id 'AVAST_AV_CB_MIGRATION_SOFT_NAG' started.
[2020-09-21 19:29:58.455] [info ] [opm ] [ 2400: 4496] Validate all campaign/message(s) started.
[2020-09-21 19:29:58.497] [info ] [evaluator ] [ 2400: 4496] Evaluation expressions: '137' lesseq '3' returns result '0', (operand name: 'ipm.p_lex', '').
[2020-09-21 19:29:58.497] [info ] [validator ] [ 2400: 4496] End validate message 'AVAST_AV_CB_MIGRATION_HARD_NAG' (valid: '0', nextTime: 'undefined_timeout').
[2020-09-21 19:29:58.497] [info ] [validator ] [ 2400: 4496] End validate message 'AVAST_AV_CB_MIGRATION_SOFT_NAG' (valid: '1', nextTime: 'undefined_timeout').
[2020-09-21 19:29:58.498] [info ] [evaluator ] [ 2400: 4496] Evaluation expressions: 'false' equal 'true' returns result '0', (operand name: 'product.avast.post_update_state', '').
[2020-09-21 19:29:58.498] [info ] [validator ] [ 2400: 4496] End validate message 'AVAST_AV_FREE_PUS_OPMPARAM_207' (valid: '0', nextTime: '2020-09-22 19:29:58 -0500').
[2020-09-21 19:29:58.498] [info ] [evaluator ] [ 2400: 4496] Evaluation expressions: '""' equal '"browser_incognito_enabled"' returns result '0', (operand name: 'event', '').
[2020-09-21 19:29:58.498] [info ] [validator ] [ 2400: 4496] End validate message 'AVAST_AV_BROWSER_INCOGNITO_TOASTER_TEST' (valid: '0', nextTime: 'undefined_timeout').
[2020-09-21 19:29:58.498] [info ] [evaluator ] [ 2400: 4496] Evaluation expressions: '""' equal '"user_logged_in"' returns result '0', (operand name: 'event', '').
[2020-09-21 19:29:58.498] [info ] [validator ] [ 2400: 4496] End validate message 'AVAST_AV_EDITION_CHANGED_DOWNGRADE' (valid: '0', nextTime: 'undefined_timeout').
[2020-09-21 19:29:58.498] [info ] [evaluator ] [ 2400: 4496] Evaluation expressions: '""' equal '"product_edition_changed"' returns result '0', (operand name: 'event', '').
[2020-09-21 19:29:58.498] [info ] [validator ] [ 2400: 4496] End validate message 'AVAST_AV_EDITION_CHANGED_SET_COOKIE' (valid: '0', nextTime: 'undefined_timeout').
[2020-09-21 19:29:58.498] [info ] [evaluator ] [ 2400: 4496] Evaluation expressions: '""' equal '"product_edition_changed"' returns result '0', (operand name: 'event', '').
[2020-09-21 19:29:58.498] [info ] [validator ] [ 2400: 4496] End validate message 'AVAST_AV_EDITION_CHANGED_UPGRADE' (valid: '0', nextTime: 'undefined_timeout').
[2020-09-21 19:29:58.498] [info ] [evaluator ] [ 2400: 4496] Evaluation expressions: '137' lesseq '16' returns result '0', (operand name: 'ipm.p_lex', '').
[2020-09-21 19:29:58.498] [info ] [validator ] [ 2400: 4496] End validate message 'AVAST_AV_EXPIRATION_TOASTER_PRE_AUTH_TRIAL' (valid: '0', nextTime: '2020-09-22 19:29:58 -0500').
[2020-09-21 19:29:58.498] [info ] [evaluator ] [ 2400: 4496] Evaluation expressions: '"en-us"' equal '"en-ca"' returns result '0', (operand name: 'ipm.p_lid', '').
[2020-09-21 19:29:58.498] [info ] [validator ] [ 2400: 4496] End validate message 'AVAST_AV_GEEK_ENGAGEMENT_TOASTER' (valid: '0', nextTime: '2020-09-22 19:29:58 -0500').
[2020-09-21 19:29:58.498] [info ] [evaluator ] [ 2400: 4496] Evaluation expressions: '130' lesseq '3' returns result '0', (operand name: 'ipm.p_pro', '').
[2020-09-21 19:29:58.498] [info ] [validator ] [ 2400: 4496] End validate message 'NAG_EXPIRED_LOST_PAM_AVAST' (valid: '0', nextTime: '2020-09-21 21:29:58 -0500').
[2020-09-21 19:29:58.498] [info ] [evaluator ] [ 2400: 4496] Evaluation expressions: '130' lesseq '3' returns result '0', (operand name: 'ipm.p_pro', '').
[2020-09-21 19:29:58.498] [info ] [validator ] [ 2400: 4496] End validate message 'NAG_EXPIRED_PAM_AVAST' (valid: '0', nextTime: '2020-09-21 21:29:58 -0500').
[2020-09-21 19:29:58.499] [info ] [evaluator ] [ 2400: 4496] Evaluation expressions: '130' lesseq '3' returns result '0', (operand name: 'ipm.p_pro', '').
[2020-09-21 19:29:58.499] [info ] [validator ] [ 2400: 4496] End validate message 'NAG_EXPIRING_PAM_AVAST' (valid: '0', nextTime: '2020-09-21 21:29:58 -0500').
[2020-09-21 19:29:58.499] [info ] [opm ] [ 2400: 4496] Last validation results - active message(s): 1, inactive message(s): 0.
[2020-09-21 19:29:58.499] [info ] [opm_svc ] [ 2400: 4496] Selected message(s) (count: '1') with priority '2600', placement 'popup'.
[2020-09-21 19:29:58.528] [info ] [opm_svc ] [ 2400: 4496] Send opm message refresh to client, placement 'popup'.
[2020-09-21 19:29:58.528] [info ] [opm ] [ 2400: 4496] Validate all campaign/message(s) finished.
[2020-09-21 19:29:58.528] [info ] [opm ] [ 2400: 4496] Message shown was finished.
[2020-09-21 19:29:58.529] [info ] [opm ] [ 2400: 4496] Message repeat started (message 'AVAST_AV_CB_MIGRATION_SOFT_NAG', after: '60' sec).
[2020-09-21 19:29:58.529] [info ] [opm ] [ 2400: 4496] Message repeat finished.
When it occurred this time, it was just back to being a sudden flash again, but also there was nothing new at this exact timeframe in the Event_Manager.log.