Seed: Coastal Village (-1813740965); Survival Mode; Normal Difficulty; Infinite Size; world created in Beta v1.16.0.55.

Steps to Reproduce:
1.Go to Zombie Dungeon: x2332 y31 z-535.
2.Place one torch on top of zombie spawner.
Observed Results:

Spawner continues to spawn zombies, but outside of dungeon. Add additional torches on spawner and around the dungeon. Zombies continue to spawn outside dungeon. Add torches outside dungeon. Spawner continues generating Zombies outside of dungeon.

Expected Results:

When a Torch is placed on top of spawner, it should stop spawning zombies in or out of dungeon. Adding torches to spawner and room has no effect on stopping zombie spawning.