[nox101]

> When interpolating between two rotations, the interpolation can either be performed on the Quaternion values or on the Euler Angles values.

from: https://docs.unity3d.com/2023.3/Documentation/Manual/animedi...

The default is Euler values

[hamish_todd]

From that page: "When Euler Angles interpolation is used, Unity internally bakes the curves into the Quaternion representation used internally. This is similar to what happens when importing animation into Unity from external programs"