Hi, CodingPlatypus,
The issue you encountered was related to service incident SP313226 Users are receiving an error that prevents access to any list with over 5,000 items via SharePoint Online which was resolved as of Monday, January 10, 2022, at 10:21 PM UTC.
More info: Affected users were seeing an error stating that the specified list was invalid.
Start time: Wednesday, December 22, 2022, at 7:18 PM UTC
End time: Monday, January 10, 2022, at 10:21 PM UTC
Please check again at your end to confirm if the issue is resolved and you can access the default view without any error.
Regards,
Igor