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

Below URL à

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)

http://ronaldlemmen.blogspot.com/2017/02/unlimited-redirects-or-popups-to.html

Hope it helps..