Reported by multiple users, see this forum thread

Reproduction steps: (there is a sample project in the slack thread)
1. In your Unity Project, install the Cinemachine package
2. Add a cinemachine brain component to the main camera, and make sure the Physical Camera checkbox is checked
3. Create a Timeline with a cinemachine track
4. Create two cinemachine clips associated to the main camera. In each clip, the position of the camera should be different.
5. Create a basic movie recorder in the recorder window
6. Record the timeline.
7. While recording, note that the physical camera checkbox is automatically unchecked (this is part of the bug)
8. Note on the output that the lens settings of the two CM cameras are not respected. When the second camera is switched to, its lens settings are ignored (part of the bug).
9. If you record it with Anti Aliasing unchecked, you will see that the lenses are respected (expected behavior).