Hello ,
My name is Jackson and thank you for your question.
I sincerely apologize for the issue you experience with your Teams sign in , I am a user myself and do not work for Microsoft so I understand how frustrating this is.
We can first clear the Teams cache for your device to fix the sign in issues you experience on Teams. Depending on your device type, follow the steps in the link below to clear Teams cache;
https://learn.microsoft.com/microsoftteams/troubleshoot/teams-administration/clear-teams-cache
After the clear cache step please uninstall the Teams version you have and reinstall the Teams for personal use App with the link below;
https://www.microsoft.com/microsoft-teams/teams-for-home
Also if you’re using the Teams desktop or mobile app, try using the web version as a work around. Open a web browser (chrome/edge) and to https://teams.microsoft.com/.
Warm regards,
Jackson E.