Thanks for posting here in the Google Nest Community.
I know how it feels when something isn’t working as it should, and we appreciate the troubleshooting that you did. A few things: Do you get notifications in the Google Home app that your Nest Hub got removed from your account? How frequently does this happen within the day? Were you experiencing any Wi-Fi issues recently? Is this how you did the factory data reset?
I look forward to your response.
Sweet! Happy to hear that factory resetting the device resolved the issue and thanks for keeping us in the loop. Let's monitor your device for three more days to make sure that the issue is fixed. I'll keep the thread open for three more days. Please do not hesitate to update the thread if you'll experience any issues on device.