Using it against infantry targets is, but WP use by itself does not necessarily indicate a war crime

It's commonly used by nations around the world to produce smoke for the purposes of concealment or signaling/marking

I'm inclined to believe their intended use here are as artillery spotting rounds to guage whether fire is accurate or not, it's not like Israel doesn't have plenty of more effective conventional ways to kill people if that was their goal with these WP rounds

I would probably call its usage in such a densely populated urban area reckless and callous at best but that's the name of the game in war unfortunately