The most basic use of QFont, indeed the first usage example in QFont doc itself is the constructor taking a family name:
QFont f("Times", 10);
Now in https://codereview.qt-project.org/c/qt/qtbase/+/318013 that constructor was marked as "obsolete" (?!), but now after [https://codereview.qt-project.org/c/qt/qtbase/+/354366] it generates deprecation warnings.
This is a very widely used constructor, there are very many usages in Qt's own docs, examples and autotests - are you really, really sure that deprecation is the best solution?