I used firefox as you might have guessed.
Some sites redirect to https even if you didn't specifically type that in the url
I don't think it is wise to disable HTTPS scanning in avast as you are virtually crippling the Web Shield and leaving yourself exposed. It is now rare to see sites that don't use HTTPS, so the hole in security would be great.
You should only disable the QUIC/HTTP3 scanning if you are actually having a problem with it, many browser are now supporting the new QUIC/HTTP3 protocol and more sites will presumably start using it. That article is from Oct 17, 2020, so in terms of being current security wise is somewhat old, even when the last post is from Jun 6, 2021.
Avast has its own security certificate that is imported into your browser or email client, so it isn't just any old piece of code trying to act as a man in the middle.
However that is your choice.