Thanks for posting here in the Community and for sharing with us what you've done regarding your issue. When night vision is set to Auto, Nest cameras will wait to switch between normal and night modes only when the light gradually changes. For instance, at dusk or dawn, when the lighting is marginal. Some cameras will flip back and forth between normal and night modes, making the video too light or too dark. Hit this link for more information.
Thanks for getting back to us. If possible, try moving it to a different position or restart it. In case you're still getting the same issue, we would recommend you to reset it to the factory default. Remember that after the reset all of your recorded videos will be deleted as well.
Keep us posted.
How long have you had your camera for? Is this a new concern you have been seeing? Do you have any other large light sources in the room with the camera? Please let me know.
Thank you for your clarification. I know that there was a recent update that went out to the Google Home app. Have you been able to update your app and test to see if this is working after a restart? Please let me know.