From my understanding, the second stage starts spinning just before the release of Starlink satellites to give the stack the momentum necessary for the clean separation. This could explain the loss of camera feed. Internal SpaceX telemetry is likely being transmitted over a separate channel and remains uninterruptible.
Yes, they spin it to disperse the satellites. The loss of video depending on the rotation is a good idea and indeed it looks like the video is failing frequently before the separation event as well. See https://youtu.be/HwyXo6T7jC4?t=4286
