Many skeptics have proposed that it's not unreasonable that we live in a simulation or a vat or some sort. There is a bigger universe and we are just a little universe they can watch, or so that view goes. While this is certainly outside the realms of science but not immediately wrong, I can quickly prove why this can't be the case, using quantum physics and the quantum Zeno effect.
The quantum Zeno effect basically tells us that on a quantum level, a watched pot never boils. If you constantly measure a particle with wavefunction Ψ, then Ψ can never evolve into a wave nature, and it kind of just gets stuck at its current measurement becuase you keep measuring/observing it. This seems reasonable, and it is a proven scientific phenomena (https://sites.imsa.edu/hadron/2019/12/05/the-quantum-zeno-effect-explained/).
If our universe was being observed, nothing on the quantum level would evolve to a wavelike nature due to constant "observations," but we know that's not the case, as every particle has wavelike nature and a wavelength. (If you want to say that wave nature is an illusion, then you're beyond what science can explain.) This doesn't really rule out a universe where we are passively (as in not all the time) being watched, but this logic suffices pretty well in ruling out the active observed scenario/simulation/mini-universe some people thing we are in.
Thank you for reading!