There were several requests/feedbacks describing this issue. It was confirmed, that starting from build 5.5 qDebug will print all escape characters (\n \t etc.) from the string passed with QString:
qDebug() << QString("First line text\nSecond line text"); will result in "First line text\nSecond line text".
However, the problem is, that many are constructing debug messages using QString. And it introduces some inconvenience for users who starting from 5.5.0 build are forced to use noqoute() to avoid this feature.
Why not make the new behaviour optional, something like qDebug().escaped() ?