There are several differences between naturally-generated trial spawners and player-placed trial spawners.
Naturally-generated:
A maximum of 3 mobs can be alive at once
Has a faster interval between spawning mobs (around 1 second)
Player-placed:
A maximum of 2 mobs can be alive at once
Has a slower interval between spawning mobs (around 2 seconds)
This may also be the case for ominous trial spawners.
I would expect player-placed trial spawners to function the same as naturally-generated trial spawners.
Environment
Windows 11 Home
Thank you for your report!
After consideration, the issue is being closed as Working as Intended.
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Things such as graphics, sounds, world creation, biomes, redstone, villagers, and animals may not work the same in current versions.
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