It is not completely true that having a paid version of Avast will stop Avast from spamming you. I have paid Avast One and still get lots of annoying spammy popups and messages from Avast.
One example: On my Samsung S22 Avast One is persistently putting the completely useless and unnecessary pop up stating the "Avast has you covered 24/7". I have tried unchecking all items in notifications. (Which I don't want to do as a few of those are actually helpful.) Also opted out of all improvements and offers in the privacy tab. Nothing I can find turns off this annoying Avast self-promotion that is always taking up space in notifications and at the top of my screen. I can dismiss it manually, which I do 10, 15, 20 or more times a day, but it comes back. I am ready to remove Avast from my phone because of this intrusive popup that cannot be turned off. There are also Avast messages that popup on my Windows 11 computer. Granted these are not trying to upsell me, but they are spam, they are annoying and intrusive, and it appears Avast does not let you turn them off.