First it went somewhat normally to that meme about a JoJo called The World, where the meme claims it stops time and is the strongest Jojo at standing up. And how this is exactly why it's the weakest. Not only does it suck as any attack before using that The World skill will let you kill the user, but also because if anyone stops time before the The World skill is used, they can simply kill him. But it also sucks because even once it's used and time is stopped, any skill that breaks spacetime (stopped time? whats that, is it tasty? Can I break it? Oops, I broke it~) will just break it anyway.
Then my mind ended up going to said strange area: "Actually, wouldn't quantum mechanics mean that killing someone while time is stopped ends up having them healed before time returns? Or a simpler example, say someone's head is lost (ie. Mami), and they stop time before they die from that, wouldn't it mean that they will return healed once time is restored?
Essentially, particles are described to occupy a "probability cloud" as 'part of' the uncertainty-principle/wave-function-collapse subjects (it's why iirc experiments has shown particles move past obstacles that ought to have been impossible, beyond mere tunneling (which instead relies on atoms being mostly empty space)), and so even if you are dead with head lying next to body, there is a non-zero probability for all particles making up your body to eventually find themselves in the original (or close enough) locations such that you regain both life and the Power to stop/start time (which allows time to resume).
With time being stopped for an infinitely long time, even a negligible probability becomes Certain (not actually true, more on this later). Meaning that if you die after stopping time, you haven't in fact doomed reality to be frozen in time, as eventually after an infinite number of eons, you will return to life and can resume time.
Granted, if there is any other possibility that could lead to resumption of time, that might happen before that.
As for why the above wasn't actually true, the reason relates to the same age-old argument about why infinite parallel worlds doesn't mean duplicates of ours exist: infinities can be of different size.
Add to that how the stochastic movement of the particles and energy might actually be more likely to lead in certain directions, making it less and less likely to restore your body as time passes (which we know to be true, due to laws regarding entropy).
Then add how our different body parts had different momentums, making their distance increase over time (I might have put the experiment in a frictionless vacuum, to allow for movement of Our particles despite time being frozen. As otherwise it would be blocked by the air acting as a solid (even more solid than that tbh, as you would need a literal infinite amount of force to move any particle at all). But this means it's effectively in space and the head will continue tumble away until gravity returns it - but their orbits will differ).
And we can as a result see that naively speaking no such restoration could occur.
However, we can, like I mentioned, consider gravity as a force acting to return the particles to same location. If it's in space then we need to consider orbits, but a simpler experiment is if this frictionless vacuum is infinitely vast. Meaning our world [where we stopped time after being decapitated] is completely empty except for our own body, and so having stopped time makes absolutely no difference, as there is nothing to compare/relate to (or would zero-point fields, vacuum energy, virtual particles, expansion of space, acceleration of expansion of space, and all those things [having their time stopped] matter enough to invalidate that claim? At least the acceleration of expansion of space being stopped might be important...).
Instead all we have to consider is whether our body could theoretically, after infinite time, reconstruct itself. After all, any momentum at t=0 can be ignored as what little gravity still exists (aka spacetime being bent by the mass from our own body) will pull things back together. So all we need is things aligning up properly and molecules sticking back together (or whatever allows a head to be decapitated, by breaking).
On another note, what happens to spacetime when time is frozen for everything but a single object? Is it dependent on time (as in, if a mass is at location A, then at location B, does spacetime need an infinitely short time to remove the bend at location A, or does that happen unrelated to time?)? If it is, does it leave the bend where mass was at timestop, or does it continue bending it as mass moves creating a "valley" trail along its path? Does leaving a mass at point A cause spacetime to continuously bend more and more, as if the mass is increasing (like the valley-case, except this case is considering what happens when mass doesn't move)? Other?