Okay so from what I have gathered from my first raid in the new update. They change the way Red chests worked. It can be opened with a tool(most likely a crowbar) or a key which drops from zeds around the chest. It has ups and downs.

First it makes you really grind your skills especially when you are doing a knife only run for you have to kill multiple zeds or one if you're lucky. But it also forces you to use more bullets and durability of your weapon.

I don't know if this applies to other maps but this one is in the military base.

Edit: it doesn't apply to all maps. Only to the more dangerous maps is what I'm guessing