[Bug]: Mobs keep spawning for no reason

[SushiWolfArt]

What happened?

I am playing an Essential Server with my friend, and it has fire and ice as one of the mods. After we beat the ender dragon, mobs like fairies and Stymphalians would spawn a few blocks behind (I'm the client) and just keep spawning. it started off as like one or two fairies, but kept increasing in amounts until there were like 50.
2024-12-12-4.log.gz
Modpack link:https://drive.google.com/file/d/1SI-tURB6-tbLPQi1h-u67eF4cYtTJaO8/view?usp=sharing

Minecraft Version

1.20.1

Ice and Fire version

2.1.13

Citadel version

2.6.0

Relevant log output

No response

Other Information

• I am using other mods besides Ice and Fire
• I have attached a log file from the session that I have experienced this issue