Example 1. 
Qt 5.15.2 returns both screens in Qt screen units rather than screen pixels.
6.2.4 returns both screens in screen pixels sizes

Qt Version:  5.15.2
Setup Information (1) - 2 screens (One 4K + One 2560x1440) 
Scale is default (4K = 150% - the other is scaled at 100%) 
Screen 0  geometry: QRect(0,0 2560x1440)  dpr: 1
Screen 1  geometry: QRect(-3840,0 2560x1440)  dpr: 1.5

Qt Version:  6.2.4
Setup Information (1) - 2 screens (One 4K + One 2560x1440) 
Scale is default (4K = 150% - the other is scaled at 100%) 
Screen 0  geometry: QRect(0,0 2560x1440)  dpr: 1
Screen 1  geometry: QRect(-3840,0 3840x2160)  dpr: 1.5


Example 2:
Qt 5.15.2 returns both screens in Qt screen units rather than screen pixels.
6.2.4 returns the screen size in screen pixels (which is horrible considering what it returned in example 1)

Qt Version:  5.15.2
Setup Information (2) - 2 screens (One 4K + One 2560x1440) 
4K screen is scaled default (150%) - the other is also scaled to 150%.
Screen 0  geometry: QRect(0,0 1707x960)  dpr: 1.5
Screen 1  geometry: QRect(-3840,0 2560x1440)  dpr: 1.5

Qt Version:  6.2.4
Setup Information (2) - 2 screens (One 4K + One 2560x1440) 
4K screen is scaled default (150%) - the other is also scaled to 150%.
Screen 0  geometry: QRect(0,0 1707x960)  dpr: 1.5
Screen 1  geometry: QRect(-3840,0 2560x1440)  dpr: 1.5  (NOTICE: This is INCONSISTENT with the result of example 1)


Example 3:
Qt Version:  5.15.2
Setup Information (3) - 1 4K screen - Scaled default (150%)
Screen 0  geometry: QRect(0,0 2560x1440)  dpr: 1.5

Qt Version:  6.2.4
Setup Information (3) - 1 4K screen - Scaled default (150%)
Screen 0  geometry: QRect(0,0 2560x1440)  dpr: 1.5       (NOTICE: This is INCONSISTENT with the result of example 1)