I found these steps and decided to share them with you. Not sure if this will be helpful but you can try the following:
Remove Saved Credentials:
Open Keychain Access on your Mac.
In the search bar, type in Microsoft Remote Desktop to find any related saved credentials.
Right-click on the entries and select Delete to remove them.
Reset Microsoft Remote Desktop:
Close the Microsoft Remote Desktop app if it’s open.
Open Finder, then select Go > Go to Folder.
Type ~/Library/Containers/ and press Enter.
Locate the folder named com.microsoft.rdc.mac or similar and move it to the Trash.
Empty the Trash and restart your Mac.
Reinstall Microsoft Remote Desktop:
After the restart, reinstall the Microsoft Remote Desktop app from the Mac App Store.
Set Up New Connection:
Launch the Microsoft Remote Desktop app.
Click on the + button to add a new workspace or connection.
Enter the correct details and choose the appropriate authentication method.