I don't use graphene, but you can use tools like ScrambledExif or FFShare to strip metadata before sharing pictures
Discussion
Ah, good to know!
Haven't tested FFShare yet, but I have been used ScrambledExif for quite a while. It's relatively convenient, when sharing a picture you first choose ScrambledExif in the share dialog. Then it will pop up again and you choose the app you actually want to share to. The image gets piped through and all metadata is removed, so it's just one more tap.
If it's about nostr only, some providers like nostr.build will also remove metadata automatically
Someone just told me metadata includes GPS coordinates - is this true?
Depends on the camera. Chances on a smartphone: 100%
The GPS is built in.
JPG metadata is called Exif (hence ScrambledExif)
Google some exif info tool (don't have a concrete recommendation), upload a photo from your phone and check what it gives you.
Camera model, shutter length, iso, location is common stuff