All physical evidence points to the universe containing some fixed amount of entropy which puts an upper bound on the complexity of any simulation you could embed inside it.

Given this, the claim that we're at the bottom of some large or infinite stack of simulated universes would have to also assert that the containing universe is fundamentally different than our own, which moves the claim from the realm of merely unfalsifiable to convoluted.

When I see people like musk make the argument for the universe being simulated I can't help but see those arguments as a sophomoric reach for whatever model of reality feels "coolest" at the time; evidence be damned.