To Avast, please work with Apple's developer team to get your software working.
While I realize this is a developer release as still in Beta I'm surprised to see several Anti-Virus competitor software in the Mac App Store that is compatible. I’ll reconsider installing when Avast certifies it for MacOS Big Sur. I've been a long time customer and promoter of Avast products but made the decision to remove the Avast software as it's made my developer workstation unusable. It pops this message every 5 seconds and the only way to stop it is to completely uninstall Avast. Issues experienced on MacOS Big Sur is the applications slowing the system, some applications like Avast Premium Security being unusable and a constant annoying pop up asking me to enable access for Avast Premium Security to the MacOS Firewall even though it's already set to allow. While I did not receive a response from Avast on this matter I've figured out how to manually uninstall all associated files of Avast Premium Security, Avast Secureline VPN, Avast Anti-Track and Avast Cleanup.