https://github.com/microsoftgraph/microsoft-graph-docs/issues/2624
I am experience the issue as the above.
I am trying to save the content of a page with a reference to an image by calling https://graph.microsoft.com/v1.0/users/{userId}/onenote/pages/{pageId}/content?preAuthenticated=true
Per this - Downloading one note page with image content as HTML
By appending "?preAuthenticated=true" when you do the fetch, it will make the image public.
But when I tried to render the html, it's giving me "Failed to load resource: the server responded with a status of 401 (Unauthorized)".