As the values are going to a positive value, this is a factor of quaternions and rotation in the engine. If you watch the value as it goes (It may help to use the “slomo” console command at .5 or a lower value to slow everything down) and it reaches a certain point, it’ll cause some weird stuff to occur.
As an example, if you rotate along the Z axis outside of the bounds of -90 to 90, the value will reset to the opposite side of that range and change the other values to compensate.
This is a limitation of 3D rotation in the engine due to Quaternion math. I would suggest converting all of your values to Radians prior to doing calculations as they won’t do that to you and you can convert them back to degrees afterwards.