Hi @AlexandeR TheGreaT ,
Try to provide the version number of Office you're using, please go to File- Account as shown in the following picture:
I cannot reproduce this problem in my environment, I suggest you check if this problem only appear in Teams, how about open from online and outlook attachment.
I also suggest you check if the sender can open without read-only mode.
Try to provide more information about this problem and I'm glad to help you.
If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.