When clearing a Pool of Memory trial on Kazuwari (for me it was Trial of the Changeling) characters that end combat flanked will still be considered flanked after exiting the challenge.
This flanked condition doesn't clear on restart or rest. The only way to clear the condition is by entering combat, getting flanked, and then getting "un-flanked", so to speak. As proof of this condition here's a google drive link to a zip file containing two saves: one from before the glitch, and one from after the Trail of the Changeling. https://drive.google.com/file/d/1mh45jsS6shNPxrn6X_8zhumh8ZSyOyev/view?usp=sharing