Apparently the "best practise" is using Manifest V3 versus V2.

Reading a bit online (not having any personal/deep knowledge) it seems the original extension also downloaded updates from a private (the developers) server, while that is no longer allowed - they now need to update via the chrome extension, which also means waiting for code review/approval from google.

I can see the security angle there, it is just awkward how much of an vested interest google has in the whole topic. ad-blocking is already a grey area (legally), and there is a cat-and-mouse between blockers and advertisers; it's hard to believe there is only security best-practise going on here.