I was wondering this too! So i conduct an experiment myself and found out, if you just took a photo in portrait it will auto correct it to landscape, regardless of the camera app.

So for my example, i’m using poco x3, tried using both stock camera app and pro cam x lite, took a photo in portrait, upload it, and it will rotated to landscape. So i then use the same photo, do a little editing using stock photo editor(in my case i just doodle), save it, post it, and it will remain in portrait. I’m not sure whether it’s lemmy problem or what, and i’m not sure whether they know about it or not. But anyway, i posted my finding here.

If anyone know what’s up with it, lemme know, but other than that, if you know how to report it do report it!