[joezydeco]

Qt has a chronic problem with High DPI displays, especially when mixed with a lower DPI display in a multiple monitor situation. You will never get it 100% right and when you start shipping it to users that percentage will fall quickly.

[Remnant44]

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.

[hermitcrab]

Qt 6 is supposed to handle high DPI better. Does that not apply to multiple monitors? I have not noticed any issues.