The copy on your phone is reduced to a thumnail automagically, I presume. If such a feature exists I would like to know it and enable it. ‘‘Upload’’-button will upload all your not uploaded observations on your android phone.
Afew years ago storage of an Android app could grow to 17 GB but these figures belong to the past. Good memory management saves storage:
https://forum.inaturalist.org/t/limit-cache-size-or-allow-cache-clearing-for-apps/2059/36
Probably only the last 100 photo’s are stored on your Android phone:
Instead, lets clean up after ourselves and only hold on to 100 of the most recently created local obs photos. The rest can be removed when we clean up the web image cache.
https://forum.inaturalist.org/t/inaturalist-storage-what-is-the-safe-way-to-reset/25457/13