Oddly enough it’s not a war crime to attack a military target that is using a civilian population as cover. The military action has to use the principle of proportionality to limit risks to civilians, but doesn’t ban the attack. Attacking such a site would only be a war crime if there is no valid military target.
The use of a civilian population as soft cover (as in not actively being human shields, but not getting out of the way) could be a war crime depending on the amount of obfuscation the hiding party is using. In the instance of Hamas they built their bases directly under hospitals so I’d say that meets the bar for war crimes.
Also, the current news is that Hamas is blocking evacuations from this region. So that moves it from soft human shields to forced human shields.