The irony is that Schrodinger created the scenario to point out flaws/limitations on the Copenhagen interpretation. He used it to show how universal adherence to the idea of superimposed quantum states can create a bit of a ridiculous scenario where it's possible for a cat to exist as dead and alive at the same time until observed. Even Einstein agreed that this was a very effective way of illustrating problems with the Copenhagen interpretation as nobody could credibly believe that a cat could inhabit such a state just because there was no outside observation.

The many worlds theory takes that wavefunctions don't actually collapse but exist in all states simultaneously in different worlds. It also holds that the observer portion is largely irrelevant, because whether observed or not, all possible states will play out in a given world. So, whether you're observing it or not, everything happens and doesn't happen in every way possible, somewhere. With this theory, even probability goes out the window, because every probability is validated, potentially an infinite number of times. There are multiple many-worlds theory extrapolations and variations too, not just one unified approach to it dealing with all this. I'm still trying to wrap my head around it as I dig deeper into it.

From the original post it looks like you're trying to blend parts of simulation theory as being synonymous with concepts of quantum mechanics. If you're looking through a many-worlds lens, in theory, the observer doesn't matter as to whether or not quantum events occur or how, as many worlds denies that the observer causes a collapse in waveform to determine reality. In many worlds every event creates an instance of an observer that's entangled with each possible outcome. So the bears in Siberia both exists and don't exist in every location, just as in every location there is and isn't every possible observer of said bears all simultaneously. Everything that can happen without violating the laws of physics is perpetually happening everywhere it can. It really does feed in to what seems the absurd conclusion that somewhere out there is a you (or infinite yous) that is Batman (though likely not Superman as that would tend to defy physics as we understand it).

In believing it's all a simulation with outside controls, then observer based rendering would be a matter of how the simulation codifies rendering. Quantum mechanics doesn't have to explain why something renders or doesn't anymore. It would need to apply to all things rendered but whether or not it was rendered would depend on whether the code decided there was need for it. There would also likely be something more like garbage collector routines to remove constructs that weren't needed to free up resources after the fact.

If I were to believe in simulation theory, I don't think I'd believe in an observer-based rendering simulation theory or one with limited resources that require cleanup. If everything connects on the quantum level, I have a hard time accepting that things would not be drastically and universally affected by portions of it popping out of existence to save a bit of memory. I think I'm digressing from the original post though but as soon as you throw in the concept of rendering, it sounds more like simulation than strictly quantum.