Studio is changing to use OAuth for login, matching how other IDAs relate to LMS authentication. (Previously, Studio simply shared a session cookie with LMS; this will be changing soon.)
If you’d like Studio login to keep working in an already-provisioned devstack, just run this command in your devstack repo:
./provision-ida-user.sh studio studio 18010
Let me know if you have any questions! And the relying PR is here, if you’re curious: feat: Activate Studio SSO for devstack by timmc-edx · Pull Request #28534 · edx/edx-platform · GitHub