OnePlus
Set the Rear Camera Video Resolution auf OnePlus
The rear camera on your OnePlus phone records at whatever resolution and frame rate the Camera app last used, and that setting quietly decides how fast your internal storage disappears. A clip filmed at a high resolution with a high FPS rate produces noticeably more data per second than the same clip at a lower setting, even though both look sharp on screen.
Because this setting lives inside the Camera app rather than the general system storage menu, it will not show up when you check overall device storage. You have to check it directly where recordings start.
To review or change it, open Camera app ➔ Settings ➔ Video resolution and pick the value that fits your storage budget. Lower resolutions and frame rates free up space immediately for future recordings, but existing clips keep their original file size until you delete or move them.
If storage is already full, clearing old videos or moving them to cloud backup solves the immediate problem faster than lowering the resolution. Reducing resolution mainly prevents the issue from repeating, and it does trade off some sharpness and slow-motion smoothness in future recordings.