How to Fix Azure Authentication Error 0x80080005 Caused by Update KB5074109

I run a small managed service provider and we've had quite a few users facing an authentication error (0x80080005) while trying to use the Windows App and Azure Remote Desktop. This issue seems to be linked to the recent Windows update, KB 5074109.

To resolve this, you can follow these steps:

1. Block the update to prevent it from being installed again.
2. Remove the update from the system.
3. Reboot the workstation.
4. Users should be able to get back to work after this fix.

To block the update using PowerShell, you can run the following command:
```
New-Item -Path "HKLM:SOFTWAREMicrosoftWindowsCurrentVersionWindowsUpdateUpdateExclusionList" -Force;
New-ItemProperty -Path "HKLM:SOFTWAREMicrosoftWindowsCurrentVersionWindowsUpdateUpdateExclusionList" -Name "KB5074109" -Value "Block" -PropertyType String -Force
```

For removing the update via CMD, try:
```
dism /online /Remove-Package /PackageName:Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.20 /Quiet /NoRestart
```

To find your package name, use this PowerShell command:
```
Get-WindowsPackage -Online | Where-Object { $_.PackageName -match '5074109|RollupFix' } | Select-Object PackageName, PackageState, InstallTime
```

After the package is removed, reboot the workstation. If users are still having issues, they can temporarily log in through the AVD Web Client until Microsoft releases a patch.