Yeah, I had the same feeling that MV3 has been rushed and is not 100% ready. The other issue as well is that Mozilla and Google roadmaps are quite different, so you might end-up having to support both MV2 and MV3 for a while at least. And even then, Mozilla will have some different APIs on MV3 (albeit they will be extra APIs when compared to Chrome).

I am looking forward to see the state of things in December 2022.