looks like rendering adblockers extensions obsolete with manifest-v3 was not enough so now they try to implement DRM into the browser giving the ability to any website to refuse traffic to you if you don't run a complaint browser ( cough...firefox )
here is an article in hacker news since i'm sure they can explain this to you better than i.
and also some github docs
Yes, Mozilla has been slowly taken over, so the time where I could stick to stock Firefox is drawing to a close. I think a useful community supported fork will emerge by that time.
The tor browser itself should just do ehat you want (without connecting to tor itself)
Yes, that is also an option I'm aware of.