OnePlus
Enable or Disable Double-Click Power Button Camera Launch auf OnePlus
The Double click the power button function on OnePlus phones is tied to the system-wide button and gesture settings, not to the camera app itself. When it is set to Camera, two quick presses of the power key launch the camera from almost anywhere, including the lock screen.
Problems usually come from one of two situations. Either the shortcut is set to Camera and keeps opening the app when you only wanted to lock or wake the screen, or it is set to None and double-clicking does nothing at all.
To check or change the current setting, go to Open the Settings ➔ Tap on Buttons & gestures ➔ Tap on Double click the power button ➔ Choose None or Camera.
Choosing Camera keeps the fast-launch shortcut active. Choosing None frees the double-click gesture completely, so it will not trigger any app.
One side effect matters for photography: when the camera is opened this way from the lock screen, swiping in from the camera view to view your most recent photo or video can behave differently than when the camera is opened normally from the home screen or app drawer. Keep that in mind if you rely on quickly checking a shot right after capturing it.

