Welcome Sophie Wang,
Thanks for reaching out to Microsoft Q&A Forum. I understand that signing in to Minecraft with your Microsoft account keeps returning you to the same page.
Does this happen specifically in the Minecraft Launcher, or does the Microsoft sign-in page also loop when opened separately in a browser? Do you receive any error message or code during the process?
Please make sure you already tried the Q&A Assist steps. In addition, please try the following.
1, Repair the Minecraft Launcher.
- Select Start, then Settings.
- Select Apps, then Installed apps.
- Find Minecraft Launcher and select the More options button.
- Select Advanced options.
- Select Repair if the option is available.
2, If Repair does not resolve the issue, return to the same Advanced options page and select Reset.
3, Restart Windows after the repair or reset is complete, then open Minecraft Launcher and test the sign-in again.
Looking forward to your update.