Sedevacantists & Novus Ordo conservatives have been arguing this for decades. Of course it’s binding if it’s a valid ecuмenical council.

R&R have a fair objection worthy of note though. Even if you accept the council, how would you obey the council’s teachings? It’s ambiguous, contradictory to past magisterial instruction, and the post VII hierarchy has been like a swinging pendulum in its application. There has been no official interpretation that one can rely on either.

It’s time to face the facts. No matter what side of the debate you’re on, Vatican II is a huge problem.