Common mistake/error message when trying to access, this is code AADSTS50085 from Microsoft documentation, but make essier for everybodoy
You can not logged or have more than ONE SharePoint’site in the site browser.

Solution of the AADSTS50085:

Solution A: Sign out the first out and sign again with different

Solution B: Using an incognito mode or private mode.

Solution C: Using different browser.