Summary
Same issue in MC-269986
The top texture of the inactive ominous trial spawner is mirrored, making it inconsistent with its active forms and non ominous spawners. This is an issue with the texture, not the model.
Addons/Resource packs: no
Attachments: Yes
Steps to reproduce
Place a normal trial spawner and then use ominous potion
Place no hostile mobs to trial spawner and then set survival mode
Go back to creative after the trial spawner is ominous and then place another trial spawner to right any rotation
Easy steps method
Use the Command in following
/setblock <Position> trial_spawner ["ominous"=true]
Place down the normal trial spawner at right nearby
Observed result
The Inactive Ominous trial spawner is mirrored
Expected Behavior
The Inactive Ominous trial spawner would like match the top texture same as normal trial spawner to make consistent top of texture
Can confirm.