They export normally from Designer. Photo messes up by adding a white border.
Setting "include bleed" in Photo's export cuts away the white border and leaves the now smaller image. Exporting 1:1 is not possible in Photo when Artboards are used.
This extra area roughly matches the frames once set in export persona (the very first thing I deleted, EP is clean).
This is through normal export, I don't use export persona anymore as it's too fickle and error prone.