I've said this before and I'll say it again. The problem with coming up with a test for being in a simulation is that the creator of the simulation might simply overwrite our memories. They could make us believe we succeeded in proving the simulation hypothesis false. There really isn't a way to test this properly when you aren't able to experience reality objectively. We're on the inside.

Side Note: I had an interesting debate just last night with some friends where I pointed out the creator of the universe might not even be aware of the aberration of our existence in it and from a high level thinks everything is running smoothly. And, we haven't made a big enough dent in the universe to get noticed. The question then becomes, if we for example destroyed a star or entire solar system to get the creator's attention would they go, "WHAT IS THIS?!" and delete the aberration? Contact us? Or, simply observe? Note: I was discussing a real god at the time, but my friend thought I was referring to a creator in the context of simulation theory at the time. Still an interesting brain buster either way.

Also, if it's true the creator is more of a macroscopic thinker than microscopic and are "asleep at the wheel" then it kind of explains a lot of things regarding injustices in the world. The creator just glances at the universe from time to time says to themselves, "Well, the galaxies are still spinning. All is well."

No offense to any religion. It was just a fun thought experiment.