I haven't had a high DPI issue with QT in quite a while. Early in QT 5, high DPI presented many problems, but they have been slowly settled over time, including

I haven't had a high DPI issue with QT in quite a while. Early in QT 5, high DPI presented many problems, but they have been slowly settled over time, including by using sane defaults. Source: I develop a QT widget app and develop on a workstation with mixed high and low DPI monitors.