Pretty much all of my "family tech support" is related to the AV doing something stupid like auto-deleting cookies or flashing up big scary messages for something trivial.
However Windows Defender seems to be good for me on Win10 - it just sits there out of the way, I don't even know its running. I LIKE the fact it doesn't have "online protection" or password managers or parental controls or whatever. It feels lightweight and does not cause everything to become 3x or 4x (or worse!) slower like every other AV software I've encountered
Whenever I go to perform family tech support I remove any random AV software they've been tricked into installing and just leave Windows Defender and that usually solves the issues (obviously making sure they are up-to-date on patches & still using 2FA)