Unable to reproduce, the game rule works as expected for me.
Can confirm for 1.21.8
Confirmed for 1.21.6
@mixquartz My command works perfectly fine in the latest snapshot (25w09a).
If you’re looking for the 1.21.4 format, you can use this:
/summon text_display ~ ~ ~ {text:'{"translate":"key.mouse.left"}'}
Confirmed for 25w09a
Can confirm for 25w04a, 25w05a and 25w06a.
Can confirm for 25w04a, 25w05a and 25w06a.
Confirmed for 25w03a
Can confirm for 25w03a
Confirmed for 1.21.4 and 25w02a
Confirmed for 1.21.4 and 25w02a
Can confirm for 24w46a and 1.21.4 Pre-Release 1
Confirmed for 24w46a and 1.21.4 Pre-Release 1
Confirmed for 24w45a
Can confirm for 24w45a
Can confirm this behavior in 1.21.3
I support WillChill's idea to add a new gamerule to control Monster Spawners and Trial Spawners separately from natural mob spawning.
The doMobSpawning gamerule would not affect any of the Spawners, and the new gamerule could be named spawnerBlocksEnabled (similarly to commandBlocksEnabled), or even doMobSpawningFromSpawners.
Confirmed for 24w44a
@bewketu bellar
Do note that there is a distinction between “Open” and “Working as Intended”.
Since the spawnMonsters game rule works different from the spawnMonsters server property, and that this wasn’t disclosed in the snapshot, I think it is fair to assume it is a bug.