No. Because you have never seen a universe of which you are sure that it was a real universe, so you do not know how a real universe behaves, so you can not det

No. Because you have never seen a universe of which you are sure that it was a real universe, so you do not know how a real universe behaves, so you can not determine whether our universe behaves differently than a real universe. You are just postulating without justification that in a real universe time progresses uniformly and then conclude that our universe is not real because time does not progress uniformly. As I said in a different comment, even if the stars in the Milky Way suddenly rearranged themselves to spell out »You are in a simulation.« on the night sky, you could not tell for sure whether this is a message from the simulators in the outer universe or whether this is just some weird behavior arising from the laws of physics in a real universe.