This seems to be related to MobSpawning.A Temporary fix is using a programm like https://irath96.github.io/webNBT/ to edit the level.dat, and set the gamerule "doMobSpawning" to "false".
Attached it, including a screenshot
It works like an block updater and i dont think the observer is meant to be doing this
This seems to be related to MobSpawning.
A Temporary fix is using a programm like https://irath96.github.io/webNBT/ to edit the level.dat, and set the gamerule "doMobSpawning" to "false".