the camera will auto drift up and to the left, and R2 and L2 will go against the auto drift at different strengths depending on how hard they are being pressed, you have to hold both triggers at half of the full pull to keep the camera still. i have found that turning on "touch only effects hotbar" in the settings turns this drift off, but if you press R2 or L2 again, the camera will drift either up or left respectively until the controller is disconnected from the phone.
Thank you for your report!
We're actually already tracking this issue at MCPE-18432, so I will resolve and link this ticket as a duplicate.
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