Hi Quan,
Sorry to hear about the sign-in trouble with Power Automate Process Mining Desktop App. If the issue still remains to help you out, could you please reproduce it and then shortly after that share the application log with us?
You can find it at C:\Users\{UserName}\AppData\Local\Microsoft\Power Automate Process Mining\Logs\Application.log.
This will give us more insights into what might be causing the issue. Thanks!