To be more precise: The absence of ashtrays fluctuating in Morse code and spelling out messages or other clear signs of influence is not evidence of the absence of meddling.

We can not realistically know whether or not someone is meddling with a simulation we are in because there are infinite ways they could do so that would be indistinguishable to us from "just the way the universe is".

E.g. for what we know quantum mechanics is an artefact of ways of optimizing the simulation, for example.

But at the same time, there are clearly an infinite number of ways those running such simulations could make their existence quite obvious if that was the intent.

And frankly that is one of my biggest issues with the simulation argument. Let's call it the Fermi Paradox of the Simulation Agument: If we're in a simulation, where are the obvious signatures of these "simulation masters"?

Because if simulations of consciousness eventually becomes possible, I have a hard time of seeing how they'd not eventually become "cheap enough" with sufficient shortcuts that we'd be more likely to live in a far future version of The Sims than a serious scientific simulation.

And have you seen what people do to their Sims on Youtube?

If we are in a simulation, then I wonder why in the world things are not more messed up. Why hasn't some immature "simulation master" written their name across the night sky with giant fluorescent penises, for example. (Then again, maybe that's in the next simulation over)

"Observation contradicting previous knowledge" is literally the point of experimentation. If gravity were to do such a thing, either A) it was indistinguishable from random chance and we incorporate a concept of uncertainty into our understanding of gravity (which has actually happened), or B) it'd be reproducible and we'd... update our understanding of gravity (which has also actually happened). In neither case do we receive information we can use to determine "meddling".

Flaming letters in the sky stating "This is a simulation"?