My WatchOS 7.3 Adventure

I've had similar problems for the past year and a half with updating. Apple has a support document[0] that suggests unpairing and repairing to update the watch.

I've also seen the photo count be wrong for several years. Mine shows 34 photos installed in About, but the photos app only shows 19, and the in the album on the phone that is synced to the watch contains 19.

I've had another problem where the watch would run itself out of disk space (not sure what it was, my theory was crash logs or something like that) and then lock up hard requiring a hard reset. Took several months for this to happen, but was consistent for several firmware updates.

I've used the Apple Feedback Assistant to provide logs and on this. But I don't think it's fixed in 7.3 yet. I've lost 500MB of available space since installing 7.3, with no new songs, photos, or applications installed since installing 7.3.

[0] https://support.apple.com/en-us/HT211283