@Ly1
Google Nest's online Help says (under "Remove other people from a home"): "If the person you remove from the home migrated their Nest Account and devices to a Google Account, those devices may be removed from the home. Data associated with their Nest devices and the home may be permanently deleted, including video history footage and thermostat settings."
https://support.google.com/googlenest/answer/915535
If that's what happened in your case, I think the video history is deleted, and you may have to factory reset and reinstall your devices.
