> we would simply interpret it as a law of physics.
And that would be in some sense sensible and perfectly correct.
> We would only recognize it as a "glitch" if we had a specification to compare it to,
Nah. I disagree. If you are playing a game and you fall through a wall you can call that a glitch without seeing the game's specification. It is because that experience is not in line with the rest of the system.
Imagine if we find that a specific reaction between high-energy particles goes measurably differently in one bounded patch of the universe. We find this randomly. Then an army of physicist descends on it. They measure a lot. Perform experiments. They characterise the effect to a high degree. Map out the precise boundaries. Map out what exactly happens on the boundary, and so on and so on. ... Is this just physics? Yes! Would this effect feel like a "glitch"? Also yes!
> I don't understand what "gaining root" would mean either.
Transcending the laws of our Universe. Being able to change them. Rewriting the very fabric of reality. Becoming god or gods. Peaking behind the curtain and finding a brand new playground beyond it. Being able to change PI to be actually 42.
> To me this seems like solipsism
I think you are hang up on some specific flavour of how the universe could be a simulation. Maybe try to think of other possible ways?