Bug Previous state in animator affecting current state keyframes?

I have two animations on an object (tested with a cube), where one doesn't have rotation in the y-axis keyframed. I would expect that when the second animation is playing, I can rotate the object around the y-axis. However, if the first animation is applied to the object in an animator before the second one, I can't rotate the object. If the second animation is the only animation, I can do the rotation.

First animation keyframes:


Second animation keyframes:




Animator with both animations, with a boolean transition so that the second animation always becomes active, but the first animation is the default state, where the rotation in the y-axis doesn't work when playing:


Animator with only the second animation, where the rotation works when playing:

Attached also a minimal example project here, with Cube in the scene having the animator with both animations and Cube2 having the animator with the second animator.

Any solutions on how I could also be able to rotate the object in the y-axis in the second situation? Why is the previous state affecting the object's animation keyframes?