It could be that this is a user error, because version control on the scene might not be recommended.

https://forum.unity.com/threads/cinemachine-object-is-different-across-machines.1012285/#post-8121167

Reproduction Steps:
In a nearly empty scene I reproduced the issue.

1. Create scene and add a Cinemachine camera and an empty GameObject.
2. Set Aspect ratio to 16:9 in Game window
3. Commit to Git.
4. Change aspect ratio to 16:10, make any edit to the GameObject (like position), and save the scene.
5. Observe in Git that the only pending change is the GameObject.
6. Add a Cinemachine Virtual Camera. Repeat steps 2 through 4.
7. Observe in Git that there are now pending changes to the m_SensorSize on the virtual camera.

So this seems to be occurring only on virtual cameras, and only when you've changed the aspect ratio (or resized the free aspect) from what's in the Git repository, *and* made any other edits to the scene before saving.