Not surprising for them to drop MV2, I expected it to happen even sooner, you would have to go out of your way to support MV2 extensions on chromium based browsers, and I do not see a reason for Microsoft to do that.

I get the impression that people want MV2 primarily for better ad/script blocking, but maybe the more secure and efficient way to go is to have built in adblocking. Firefox recently integrated adblock-rust, but you have to enable it in about:config and add filters manually, it seems very experimental and barebones at this moment compared to how it works in brave, for which it was written originally. It is probable some firefox forks expanded on this feature.