Excessive passive mob spawning in Purpur 1.21.3

Hi, I updated my server from 1.21.1 to 1.21.3, and suddenly had way too many passive and neutral mobs spawning. I even tried reducing the numbers in bukkit.yml, and it's gotten even worse! In some places it's a solid mass of mobs, that strangely seems to stop at some chunk borders.
https://mclo.gs/jFk2PeS