Malformed Tag

After migrating assets to a new project, we get thousands of errors of “malformed tag”. What is this? Can anyone help?

We had this issue in relation to a texture.
There was a version we could see in-editor that worked and a version we could not see in the editor that caused the malformed tag error.

I suggest looking for the asset in-editor based on its path, then doing the same using a file manager.
If it is not visible in-editor, but exists in the file manager, deleting the file should solve the issue.