We all have faced this issue where Dynamics 365 keeps opening the login page in the new tab.
If we check the URL it is basically redirecting to --> https://ourwebsite.com/Auth/v2//authRedirect.html#id_token=[token]&session_state=[guid][token]&session_state=[guid]
To disable this behaviour for all the users, disable the learning path.
Set Enable Learning Path as No.
For individual user, select Opt Out of Learning Path from Personal Options.
https://docs.microsoft.com/en-us/previous-versions/dynamicscrm-2016/admins-customizers-dynamics-365/mt826648(v=crm.8)?redirectedfrom=MSDN
For Internet Explorer (without changing above settings):
Guide to Unlimited Redirects or Popups
