Structure (Mob) Spawning Columns Are Appearing in Pre-Existing Chunks

Summary:

Some structures in Bedrock (like ocean monuments and pillager outposts) have fixed spots where their mobs spawn (spawning columns). Normally, these spawn spots are created when the structure first generates.
After updating to v1.21.130, I’ve noticed mobs such as guardians and pillagers spawning in areas that never had those structures (because the chunk was generated long ago). When I checked with tools like Chunkbase, these locations match where the current version would place those structures. This suggests the game is adding spawning columns to old chunks based on the new structure layout. It is safe to assume this involves all spawning column based structures:

• Outposts

• Witch Huts (untested)

• Ocean Monuments

• Nether Fortresses (untested)

My existing guardian farm still works, so this isn’t removing old spots; just adding new ones in places that were previously safe.

How to Reproduce:

1. Open any old Bedrock world (chunks generated before the current structure layout, e.g. pre-v1.18.0).

2. Use Chunkbase with the world’s seed and current version settings to find where monuments or outposts would generate now. Only check in older chunks, where those structures never originally generated.

3. Go to those coordinates in v1.21.130.

4. Observe guardians/pillagers spawning, even though their respective structure was never originally generated there.

Actual:

New spawn spots are being added to old chunks, causing these structure-based mobs to spawn where no structure ever existed.

Expected:

Old chunks that never had these structures should stay the same. No new spawn spots should appear.

Implications:

• Unexpected hostile spawns in old bases (e.g., a ghost outpost inside a village build).

• Could keep happening whenever the structure generation changes, making the problem worse over time.

• Once these spawn spots appear, there may be no way to remove them without affecting genuine old structures.