This is really messed up. I do work for a medical communications company, and their app uses critical alerts. Patient safety depends on this. This change that Apple made means that provisioning profiles were pretty much silently losing the entitlement that allowed critical alerts to work. This means recent builds in the app store may not be receiving critical alerts. Which means Apple has put patients' lives at risk with the boneheaded change. Seriously stupid on their part. I hope somebody for Apple is reading this ...

In case anybody else runs into this, I figured out what I was doing wrong. Xcode 15 added a new step at the beginning for distributing an archive. I was choosing "TestFlight & App Store" in that first step (which seemed to make sense). I just tried choosing 'Custom' instead, and that takes it to the normal workflow for uploading an archive, and it works from there.