Implemeting support for v3 is not the same as dropping web request blocking API from v2... Google pays to Mozilla for service they provide having them as default search engine - it's not a sponsorship...
Saying that, I've done some more recent research and Google has already softened their stance on requests blocking with current manifesto proposal of up to 5k dynamic rules with a proposal to extend up to 30k being popular.Sources: https://developer.chrome.com/blog/improvements-to-content-filtering-in-manifest-v3/ proposal: https://github.com/w3c/webextensions/issues/319#issuecomment-1682073791
To be clear Google has no direct way to force FF to do shit. The reason Google is implementing v3 is to disrupt adblocking (by dropping v2 APIs) the reason Mozilla is supporting v3 is to make life easier for extension Devs. They don't have to comply with same restrictions