Hi Fabrice,
When you add an Excel File in the File Tab of the entity, it will be stored in SharePoint.
I think that you have configured the connection between SharePoint and Dynamics 365.
In this case, I propose this solution that can resolve your problem.
You create a Cloud flow Power automate :
Your trigger will be : When a file is added or modified in share Point.

You must indicate the site Adress where your file will be added and the Folder.
Then, you inialise a variable that contains your file Name and get the metada of your file


Try to implement this flow and tell me if that resolve your problem