Hello @Mostafa ,
1.A temporary workaround may be to disable NLA; Besides, what's the version of your Remote Desktop client for Mac? Try to update it to the latest version: https://install.appcenter.ms/orgs/rdmacios-k2vy/apps/microsoft-remote-desktop-for-mac/distribution_groups/all-users-of-microsoft-remote-desktop-for-mac
2.Do you use .rdp file for remote? Have you tried to reboot the mac and reconfigure the .rdp file by exporting and importing again?
https://learn.microsoft.com/en-us/answers/questions/224756/remote-desktop-app-on-macos-big-sur-not-working-wi.html
3.Make sure you typed the Mac username and password correctly.
In some cases, you may need to reset the password for the account in Users & Groups preferences. To reset the password, choose Apple menu > System Preferences, then click Users & Groups.
Make sure you typed the Windows username and password correctly.
The password for the Windows user account you’re using may need to be changed on the Windows computer.
In some cases, the Windows computer may need to be restarted after the password is changed.
https://support.apple.com/en-gb/guide/mac-help/mchlp1665/mac
Best regards,
Leila
If the Answer 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.