That sounds like your Galaxy S24 Ultra's back glass is separating on its own. This usually happens due to battery swelling, which is a serious issue. If the battery expands, it pushes against the back panel, causing it to detach.
You're not alone—this has happened with some Samsung devices before, especially after prolonged use or exposure to heat. I recommend:
Stop using the phone immediately—a swollen battery can be dangerous. Check for any warping or bulging in the middle of the phone. Do NOT try to glue it back—this won’t fix the real issue. Take it to a Samsung Service Center ASAP for a battery replacement.
If your phone is still under warranty, Samsung might replace it for free. If not, a third-party repair shop can replace the battery at a lower cost.
As per your query, we would request you kindly visit the service centre and inspect your device with the technical team end, they will provide you with all the information in a better way after inspecting the device physically.
