Trial Vaults cannot be opened in Survival Mode in version 1.21.7 even if the challenge has been completed and the Trial Key is in your possession.

In version 1.21.7 of Minecraft Java Edition, Trial Vaults (reinforced chests) cannot be opened in Survival Mode even if the Trial Spawner challenge has been successfully completed and you have a Trial Key. I tried the following: Activate a spawner in a Trial Chamber in a Survival world. Complete the entire battle without dying. Obtain the Trial Key from the battle. Approach the spawned Trial Vault (which appears next to the spawner). Expected result: The chest opens with the key. Actual result: The chest does not open, and no message or sound is displayed. Right-clicking has no effect. I tried the same procedure in a new world in Creative mode, and the Trial Vaults do work as expected. That's why I think it's a survival-specific bug or a world condition. Additional Notes: This bug didn't occur in previous versions like 1.21 or earlier snapshots (like the one that featured the Happy Ghasts), so it may be related to update 1.21.7 or later.