this seems to be the same thing as https://forum.inaturalist.org/t/rotating-phone-during-photo-preparing-makes-photo-lost-from-observation/45714, and it might be related to https://forum.inaturalist.org/t/android-app-seems-to-be-unnecessarily-reloading-information-on-observation-page-after-rotating-the-phone/14943
the photo might still be in the photo repository on your phone. so you might be able to manually add it back to the observation (or a new one).