Definitely because of the export and import, it turns out. The Pleroma.Web.Endpoint configuration was lost in the round trip.
Current setting is:
config :pleroma, Pleroma.Upload, [uploader: Pleroma.Uploaders.Local, base_url: "https://distraction.party/media", filters: [Pleroma.Upload.Filter.Dedupe, Pleroma.Upload.Filte…
It is not limited to a single image or even media type (I've tried jpeg, gif, and png).
Roughly concurrently with the upgrade I went in to "fix" my frontend configuration, managed to corrupt…
This is maybe a version requirement more than it's a bug, but I didn't see it documented anywhere that the new features required elixir >= 1.14. Maybe just note it in the release notes?