Hi,
I have this situation:
I change rotation of the transform with Quaternion.Euler(), only change is to rotate in z-axis with 1 unit.
Euler Angels of rotated transfomr are 90,90,0.
But after rotation they are set to 90,89,0.
Expected result is 90,90,1.

Please help me to understand this.
Thanks in advance for help.

Itâ€™s because theyâ€™re the same rotation. If you read the documentation on eulerAngles, it talks about this. To directly quote the page:

â€śUnity converts the Quaternionâ€™s internal representation of the rotation to Euler angles. Because, there is more than one way to represent any given rotation using Euler angles, the values you read back out may be quite different from the values you assigned. This can cause confusion if you are trying to gradually increment the values to produce animation.â€ť

You can go into the Unity Editor and set these rotations yourself on an object and see theyâ€™re functionally identical.

Yes, thanks, you were right - it exploded my brain and didnâ€™t help
I used Pivot Editor to normalize (I donâ€™t know if it is a proper name for that) axes.
And it almost works, but when I change X axis from 89 to 90, when Y and Z had some values, Y and Z changes to weird values. Yes, I know it is Quaternions magic. But could you please tell me how to solve this problem?

The main goal to achieve is to have the possibility to rotate the model in 3d with Euler (normal for the user values).
After docs on eulerAngles I think it is not possibleâ€¦