Hi,
I don't have a specific solution for your issue, unfortunately. I have projects using mediapipe that I have come back to and found that there have been a number of changes to both Mediapipe and Pythoner compatibility that required rewinding and using an older, supported Mediapipe and Python version (such as Python 3.10) to avoid dependency conflicts.
My Mediapipe projects have been usable again after doing that. Linked here is a Mediapipe face-tracking patch in Isadora 4.5.1 but it was made before a json/pyhthoner skeleton decoder actor was available, so the face marker decoding is scripted manually using a Text Parser actor.
Best Wishes
Russell