Hello Djiby THIAW [SNT DSI/INS/IRCP],
Thanks for posting!
As per my testing, I am able to replicate the error message when I use the bearer token instead of using the access token present in short-lived embeddable URL, please refer below screenshots for better understanding:
Below is the screenshot with access token present in short-lived embeddable URL( getUrl).
Reference link: https://learn.microsoft.com/en-us/graph/api/driveitem-preview?view=graph-rest-1.0
Hope this helps.
If the answer is helpful, please click Accept Answer and kindly upvote. If you have any further questions about this answer, please click Comment.