How recent was this? Did they change your hours or your duties significantly or show favoritism in how they treated another employee in your pre-existing role?

People who actually do quit in that situation may have a claim for constructive dismissal.

Forget about the third-party assessment, how do you think you were doing?

That sucks.

All I can say is polish up the ol' resume and start searching while you have the security of a (shitty)job