Regional Threading Bug with Server Freeze

Stack trace

I built a very large Guardian farm on a Minecraft Folia server that uses Nether portals to move Guardians to the Nether and then back to the Overworld.
The issue only occurs when entities are teleported back from the Nether to the Overworld.
After the farm enters the despawn sphere, the following happens:
A few seconds later, the server console starts spamming error messages (see logs below).
Nether portals completely stop working (for both players and entities).
After some more time (seconds to minutes), the server becomes even more unstable:
In creative mode, it is no longer possible to break or place blocks.
Entities cannot be interacted with or spawned properly.
Persistence:
The issue persists even after restarting the server.
The only way to fix it is to manually delete the affected Nether chunk entity files:
<world_name>/DIM-1/entities/<affected_chunk_file> (the area where the farm is located in the Nether), and then restart the server.

Additional notes:
While the server is in this broken state, it continuously outputs error messages in the console.
The problem seems to be related to entity handling across portals under heavy load.
Steps to reproduce (approximate):
Build a large Guardian farm using portals (Overworld → Nether → Overworld).
Ensure a high number of Guardians are constantly teleported.
Let the farm run until it enters the despawn sphere.
Observe console errors and portal failure.

latest.log

Plugin and Datapack List

Paper Plugins:

• GGQOL, Tweaks, Worlds

Bukkit Plugins (12):

• Chunky, CommandAPI, CoreProtect, CustomAnvil, EternalCore, packetevents, PluginPortal, ProtocolLib, SingleSleeper, VillagerTradeEdit
  [20:23:38 INFO]: WorldEdit, YskLib

Actions to reproduce (if known)

Build a big Farm(Guardian) with teleportation to the Nether and back.

Folia version

[20:25:45 INFO]: This server is running Folia version 1.21.11-14-ver/1.21.11@529aabc (2026-02-22T20:22:23Z) (Implementing API version 1.21.11-R0.1-SNAPSHOT)
You are running the latest version
Previous version: 1.21.11-12-6d795a8 (MC: 1.21.11)

Other

No response

Start with the attached latest.log and reproduce the Guardian farm's Nether-to-Overworld teleport flow under heavy load until the despawn sphere is reached. Trace the reported entity and portal errors, then verify that portals, block interactions, entity spawning, and persistence remain functional without deleting Nether entity files.