This in itself is actually pretty normal - banning rainwater collection is mainly to stop people from collecting so much rainwater that they cause environmental issues. At least that'swhy it's banned in many places in the US. If it's really banned in Gaza "because rain is the property of the Israel" then that's absolutely wild, though.

This may be the least oppressive and weird law the Israelis have restricting the rights of Palestinians, at least until they deliberately destroyed civilian water infrastructure. But then, I don't think enforcing rainwater collection bans is exactly at the top of the Israeli military's checklist right now.