First, I’m an Avast user and not an Avast Team member.
You don’t mention any internal UI settings that may be overriding Silent Mode (though in reality it shouldn’t) ?
You don’t mention what you were doing at the time this screenshot occurred ?
Managing pop-up notifications in Avast Antivirus
- https://support.avast.com/article/antivirus-popup-notifications/#pc
- Scroll down to Stop offers for other products. - If you use Avast Premium Security, you can additionally stop seeing offers for other Avast products and Personalised Discounts. ** Avast UI > Menu > Settings > General > Personal Privacy.
- Also check the AvastUI > Menu > Settings > General - Notifications, I would suggest using the Pop-up Notifications treatment - Limited Mode.