Hello, I'm and end user like you and I have been a user of these cameras for a long time. That sounds very odd. Would it be possible to post a picture of what you are seeing? do the red lines appear in both day light and night vision?
Are you using a Nest HELLO (generation 1) doorbell or are you on the newer generation 2 version?
As a first-step in trouble shooting you might try removing the power to the camera for about a minute and powering it back up and seeing if it self-resolves.
