1.20.1 forge modpack with alexmobs and industrial foregoing

I have a mobfarm built in the nether using mechanical dirt (works like cursed earth from back in the days; it spawns a mob from the pool of naturally spawning mobs in that region) and mob crusher from industrial foregoing.
The chunks are chunkloaded via the ftblib chunk claim map thing.

After some hours it seems like that somehow alexmobs:bone_serpent_part entities accumulate in the chunk of the farm. If I afk next to the farm it does not seem to accumulate them.
Around 10k alexmobs:bone_serpent_part entites grind the server to a halt and i have to remove the entites from the save file.

I tried to clear them with the kill command.

• kill @e[type=alexmobs:bone_serpent_part]
  • => kill 10000 entities
• kill @e[type=alexmobs:bone_serpent]
  • on the same save kills nothing

I suspect that the entities alexmobs:bone_serpent_part wont get removed when the alexmobs:bone_serpent "main" entity gets killed by the mob crusher.

It seems their might be different behavior when a player is nearby.

Limiting the entity spawning with the mod InControl or issueing a kill command every 10 minutes using mcfunctions from a datapack, did not work as a workaround.

If you need more information or want me to do some specific investigation please let me know. I would love to help.