iPhone shared albums missing, 'unsubscribed

When you say you changed your location, did you change to a different country, or just a different area within the same country? Did you have to change your Apple Account to a different area's store or currency? I'm looking for something that might make the shared album servers think your device is associated with a different entity now.

OK, so not just a different country but a different region of the world. I cannot at the moment find an Apple document that says that would trigger the behavior you describe, but it might.

I'm just another user, here trying to be helpful (like many of the senior folks here). If you want an official answer, you can ask actual Apple Support staff through the Support link on this page. (It's at the lower left corner in my browser, but I understand it may be in the upper right sometimes.) No idea whether the front line staff there will know the answer to this uncommon question.