A family of Microsoft word processing software products for creating web, email, and print documents.
Dear User932045
Thank you for your quick response.
I'm sorry I didn't explain it clearly in the above reply. I read your post carefully, per your update, it seems that when you apply the label to the document with your M365 account then if you add your google account and want to open the same labeled document in google docs, you got the error message, and the file can't be open.
Given this situation, per our search, this behavior maybe happened because the Microsoft sensitivity label is incompatible with google document due to the google doc is a third-party product to Microsoft. Apologize for the inconvenience caused.
In this scenario, if you want to open the document in google doc, you could remove the label in this document then upload the file to google doc and open it.
To remove a sensitivity label that has already been applied to a file, unselect it from the Sensitivity menu. Detailed information to remove the label, please refer to Apply sensitivity labels to your files and email in Office - Microsoft Support
Besides, we'll report this behavior to the related team and hope they can improve the Microsoft products compatibility with other third-party products as soon as possible.
If you need any further assistance, please feel free to post back.
Sincerely,
Stacey | Microsoft Community Moderator