When Ubuntu is installed on an ASUS Q502L laptop, the orientation of the accelerometer mounted inside the screen may not be configured correctly. This manifests as the screen rotation always being in the wrong orientation when rotation lock is off; it's as if the direction of gravity is some direction other than downward.
This problem is fixed by overwritting the rotation matrix that describes the orientation of the accelerometer relative to the screen.
To fix this problem, add the 61-sensor-local.hwdb file
in this repository to the /etc/udev/hwdb.d/ directory
and restart the computer (you may need sudo privileges).
This sets the accelerometer orientation for iio-sensor-proxy.
These references are where I learned how to fix this issue:
Changing the way automatic screen rotation works in Gnome shell