Hi,
Well, malicious extension, maybe but i don't know why Firefox could let such extension to be downloaded on his server.
What also noticed it that there was no such warning message on the previous version too...
I disabled all my add-on.
Re-activate each one by one, and no more warning message from Avast at 6:30am French hour
So bad ad-on or bug of detection, or new update of one of add-on make Avast be quiet???
Will shut down the laptop around of 6:50 and start it again around of 8:45 and will see if it's ok or not.
Gerald