@Alex-Patterson
Indeed, you are right, it is because of the scope configuration, whose default values have changed. The advice in the release notes regarding this in version 1.50 also sounds appropriate in retrospect.
What surprises me is that these settings are relevant when I perform the oldschool login via POST /api/login, I wasn't aware of that...
Thanks for the tip! I would probably have been looking for the difference for a while...