Has anyone asked whether the Palestinians in Gaza want out of Gaza? That seems like a more important question.

They want to return to their homes from before the Nakba. They tried to march for this peacefully in 2018 and had snipers shoot their kneecaps out.

They tried to walk through a militarized border fence, which will get you shot. If they had got to the homes they meant to reclaim the 'march' would have been anything but peaceful.

Border guards usually just deny entry and turn them away without blasting out their kneecaps.

The real question is: why is there a militarized border fence and who is paying for it?

Many of them have demonstrable property ownership (or their parents/grandparents did) in Israel proper.

they don't, in general

but they also don't want to die, want flowing water, food, electricity, medical infrastructure etc.

Egypt may well believe that (and others have rightfully pointed out that not following UN conventions for refugees is outside of the jurisdiction of the ICC), but I don't think there is a plausible case to be made that refusing to help people wanting to flee from armed conflict can be considering "supporting ethnic cleansing".