For a week or so, the firewall asks everytime if icarus.exe can connect even an allowed rule is set

Which Avast product do you have Free or Premium, also which Firewall i.e. Avast Firewall, Windows Firewall or other?

I have done a search here on the forum/community and found this from an old Beta release note for 20.7.2421 (build 20.7.5509), so was maybe a problem in the past, but I have no seen no other reports of icarus v firewall issues recently: