I'm doing a rig and faced with the following problem. The bone and it's parent have no any constraints or driver, but the bone changes it's roll even in Rest Pose. I see that at first time.
And file: https://drive.google.com/file/d/1WMr0iYCVd6Oq_r9mt8lo9fNM8D6hz3x3/view?usp=sharing
Any idea what's going on?