Safari's extensions had a similar change-over to a ManifestV3-like system, with the same arguments: increases performance (very important for mobile) and puts more safeguards on extensions doing funky privacy-hostile stuff.

Yes, ManifestV3 nerfs adblocking, and Google loves that side effect. It will hamper Brave' internal adblocking engine.

I think the big interesting question is: if Brave figures out how to add improvements to ManifestV3 that aid adblocking without sacrificing performance or privacy/security, will Google accept the PRs?