[2023] What the hell is with zombie spawn?

Originally posted by Ogami: Was a necessary change to improve performance.
Before all zombies in the building spawned from the start which dragged down the performance a ton, especially in large buildings.
Now they only spawn in if you cross certain trigger points.
It also helps with clearing zombies quests and prevents some lone zombie somewhere who wandered off to be the final target you cant find.
Combined with the new tier 6 quests and the new "clear infestation" quest that spawns a ton of zombies it was the only way to make those playable if you dont own a NASA super computer.
Yes, it sucks for stealth builds but the game has been becoming more streamlined for a while and this is cleary the path the devs have decided on, liking it or not.

I think it's more likely that the OP is talking about the fixes for quests what make it so that the zeds are auto-triggered when the trigger is destroyed.

See previously, you could stealth most POI's completely unnoticed. all you really have to do is smash those trigger piles instead of stepping on them.
It was discovered that this cwas causing an issue with zeds spawining for quests, and made it nearly impossible to finish most clear quests.
So the solution was to make the trigger occur if the trigger is activated, or if it is destroyed.

Which is the real issue for Stealth gameplay. You can still stealth through 95% of the POI, but now you need to be aware to skirt around the triggers instead of stepping on them.
There are a few where the trigger is just entering a doorway. In most of these the zeds aren't appearing in your face, but are instead spawning in hidden areas and breaking out.