What steps will reproduce the problem?

1. Claim an area
2. Unclaim the area after some time
3. Towny makes empty gaps down to void into some chunks

The chunks seem to usually be about half-empty. Most chunks are still seemingly regenerated normally, but many are starting to have gaps. Chunk regeneration has worked fine for years until now. Also our world only goes down to 0 Y.

What is the expected output?

Chunks should regenerate properly and not have empty gaps down to void.

Towny version

0.100.2.1

Server version

Paper-318, 1.20.2

Please use Pastebin.com to link the following files

1. No errors/problems in startup
2. Can't provide publicly, which part needed?

    revert_on_unclaim:
      enabled: 'true'
      speed: 1s
      block_ignore: CHEST,TRAPPED_CHEST,RAIL,POWERED_RAIL,DETECTOR_RAIL,ACTIVATOR_RAIL,TORCH,WALL_TORCH,SPAWNER,ANCIENT_DEBRIS,TNT,AIR,CRAFTING_TABLE,DRAGON_EGG,CRYING_OBSIDIAN,SNOW,MOVING_PISTON
      block_whitelist: ''

3. Can't provide publicly, which part needed?
4. Only this error has popped up, but not directly when unclaiming, https://pastebin.com/XXYbgjyj

I filled up some of the gaps (as wilderness), then we claimed them for a town and then /ta unclaim it.. and now it is regenerating back into an empty void hole again. Is the snapshot not saving properly or something? I thought it should have saved a new snapshot since it was fully wilderness.

#7316 related?

The related PR fixed empty snapshots being made in version 0.100.1.21, but any snapshots made while the issue was there will still be air

Oh we only went from 0.100.0.9 to 0.100.2.0 (which didn't load at all), back to 0.100.1.0, then to 0.100.2.1. We never had a version with the problem?
Shouldn't it take a new snapshot when claimed as wilderness now anyway? I'm unable to even plug the holes in wilderness since it just resets back to void on next unclaim

Fixed already you're out of date.

Fixed already you're out of date.

Ah, which update fixes the issue? I didn't find it in the changelogs

The related PR fixed empty snapshots being made in version 0.100.1.21, but any snapshots made while the issue was there will still be air

Issue still persists on newer versions, even in brand new claims that were never affected by whatever pre-release issue. Shall I open a new issue?