What is your account type?
Personal Account: https://teams.live.com
Organizational Account: https://teams.microsoft.comm
Based on your description, it seems that the problem only occurs on browsers. Try clearing your browser's cache and Cookies and restarting your browser.
- Open Chrome on your computer.
- Click More in the top right corner to expand.
- Click More tools, then tap Clear browsing data.
- At the top, select a time range. To delete everything, select Unlimited time.
- Check the boxes next to "Cookies and other website data" and "Cached images and files."
- Click Clear data.
If you still can't sign in after clearing your cache and cookies, try switching your network connection to check if it works.
Hope this helps! Moreover, if the above is not your scenario or I have misunderstood anything, please correct me and provide us with detailed information about the issue including the screenshot so that we can better understand to further assist you.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.