Hi, I completely agree with your request for more details.
A colleague and I have different interpretations of the change: Does it migrate to New Quizzes (NQ) by default, or does the option "Import existing quizzes as New Quizzes" appear by default during a course import/copy?
Additionally, I do not fully understand why Instructure chose to merge the features "New Quizzes Migration During Course Import/Copy" with "New Quizzes" instead of merging it with the "Default to New Quizzes/Disable Classic Quiz Creation" option. An combination of the latter two features would have seemed more logical to me since turning off the creation of classic quizzes implies that you want to move fully to New Quizzes in the shorter term.
Finally, We can't see the "Default to New Quizzes/Disable Classic Quiz Creation" name change in our Beta-environment, even though the release notes state it should have been implemented there on May 10th.