Hi everyone. The same issue happens to me, unfortunately. Can't tell if it's 100% accurate but it seems that I solved it before the latest (iOS 18) update, I've just missed the moment when this issues came back again.
As it was already mentioned, I disabled the HDR setting in the settings of my iPhone (15 Pro).
BUT! I've found that there's such setting in the Instagram too: go to Instagram > click on your profile in the bottom right corner > press the hamburger menu (in the top right corner) > scroll down to the "Your app and media" section > press "Media quality". In my case there are three toggle selectors, all of them are disabled. But pay attention to the last one called "Disable display of HDR media" - it's now activated by default, which basically means that the HDR option is enabled in Instagram. Once I activated the "Disable display of HDR media" the issue seemed to had been resolved until recently. Now I'm getting the same problem again, and yes, activating the "Low power mode" helps for some weird reason. I think this is the iOS issue, not the Instagram's.
Furthermore, here are some of my find outs:
- If you open the image in Snapseed and without any changes press "Export" - there's an option "Export" which saves a JPG copy with permanent changes. Such copy doesn't seem to be auto enhanced in Instagram. Works as a workaround.
- The same issue happens in the iPhones photo editor: just try to open the image in the editor and press "Markup" - as the result the image gets auto-enhanced. I believe this is the problem in the iOS system that causes such behavior.
-Max