I see problems on many apps, but the most on Browsers, Microsoft Office, and some apps with a rich editor.
Problems you have with Word, Chrome, Google Docs, Facebook may be things which the people who make those need to address.
I don't think so. I believe that this is a core issue of the Mac Keyboards.
Have you seen any other reports of your problem in these Apple forums?
Yes, we discussed and tried to fix it by installing some external input keyboards.
We may get the security risks for installing external input keyboards, but it is better than built-in keyboards.
I'm using Big Sur v11.6 (I had just updated from Catalina a week ago). I have another Mac Mojave, but all the same.