If you use Google Drive sync, Google Drive keeps up to 100 previous versions of your notes file. You can use this to recover lost or overwritten notes.
Click the context menu (three dots on the right side):
Select File Information → Manage Versions.
Pick the version you’d like to restore. Versions are listed by date and number, with the most recent first.
Click the three-dot menu next to that version and select Keep forever. This is required before Google Drive will let you download it.
Click the three-dot menu again and select Download.
Go to the Page Notes options page and use the Restore option to import the downloaded file.
If you run into any issues, please open an issue.