I ended up trying to restore the NC backup via the CLI, and that shows a lot more than the webUI:
Info: [#####++.............] > Restoring the MySQL database...
Exception in thread Thread-8:
Traceback (most recent call last):
File "/usr/lib/python3.11/threading.py", line 1038, in _bootstrap_inner
Warning: --------------
self.run()
File "/usr/lib/python3/dist-packages/yunohost/utils/process.py", line 157, in run
self.queue.put((self.log_callback, line.decode("utf-8").strip("\n")))
^^^^^^^^^^^^^^^^^^^^
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe6 in position 38: invalid continuation byte
Warning: INSERT INTO `memories_planet_geometry` VALUES
Which is very much the issue that Olomorn also had in this thread that you helped in! Nextcloud update failed, restore backup failed - #2 by otm33
I’d be happy to either delete the geometry table or to change the encoding… but I for the life of me can’t figure out how to do either 
Olomorn also didn’t describe it in their thread, sadly 