Cool so I just improve my images outside the app using a different app as a workaround.
This might have changed, haven't really used the app for a couple of years.
Even if Instagram does that, they can still modify the app to take pictures properly. That's definitely not a limitation with Android. The only problem I can see with this is people modifying the picture header to become the edited photo instead of a legitimate one (either with a rooted phone or a modified request on pc). There's not really any way for Instagram to properly verify this.
[0] https://www.androidpolice.com/2021/02/22/the-galaxy-s21-is-t...
E.g. people who prefer another camera app, or photographers who use a camera instead of their phone.