Photos Date Bug in Shared Album and Main Library

A few years ago I noticed that Photos had changed the dates on a whole bunch of my photos. There was neither rhyme nor reason to the change. It was a bunch of randomly selected photos from different years that had suddenly been backdated to the 1920s, as in the Roaring 20s. Well, I figured it was a typical Apple bug from their updating iPhoto to Photos, etc. I was extremely annoyed but I figured there wasn't much to be done about it, so I didn't complain. I just figured I'd get around to re-dating the photos one day but I never did. At least the photos themselves were unharmed.

Now today my sister asked me what happened to the Shared Album I had created a few years ago. I checked and it was still there, called Family, but there was nothing in it. Once again I figured it was a casualty of Apple's continual updating. So I repopulated the album and then I noticed that many, not all, and once again randomly, many of the photos in the Shared Family Album now exhibit vastly different date stamps than they do in the main Library.

So I thought I would ask about it. Is there an easy way to fix this? And once again I realize the main thing is that the photos themselves are fine, just the metadata is kafloohey. But it would be nice to if the dates would remain the same regardless of which album they are in.

[Re-Titled by Moderator]