Firefox relies on Google for its funding, so any browser based on Gecko relies on Google

Google introduced Extension manifest v3 to effectively to kill/handicap AdBlock extensions.

Mozilla, though getting funding from Google to make google its default search engine, officially decided to keep supporting Manifest v2.

Adblockers are direct challenge to Alphabet’s ad revenue which is still their biggest cash cow.

That speaks a valume about how much control google has on Mozilla decision making process.