Me too...
Old TimeCapsule, working fine since. We lost a MacBoook, so we bought a new one w/Monterey and tried to restore from Time Machine. After a couple of hours, the TM disk is "empty". Put the disk on a different driver, we can see three partitions, the interesting one is 998GB in size, choched full, and it is not possible to mount. Disk Utility cannot repair the disk, something wrong with the partition allocation map.