You may be experiencing some issues with signing in to the workspace, with a prompt from Azure AD that there are too many redirects. Not all users are affected.
We've introduced new security measures where we check if the UPN is still valid. If the UPN does not match, you will receive this error.
Update 20-11-2020 14:45 CET: We have found, located and resolved the issue. A hotfix will be deployed at 20-11-2020 22:00 CET.
Update 20-11-2020 11:00 CET: Current workaround: Update the UPN on the Azure AD side. Check if the UPN contains a capital letter and update it to small letters. If your UPN does not contains any capitals, please try to update it with a capital letter.
Update 20-11-2020 10:00 CET: We are currently working on a hotfix.
20-11-2020 09:00 CET: Investigating the issue