QApplication::font().pointSizeF() not device independent

When trying to get the point size of the default application font using QApplication::font().pointSizeF(), the value change depending of the primary monitor Device Pixel Ratio:

• With my internal 15" Laptop with 4k screen (DPR ratio = 2.5) I get a pointSizeF value of 4.8
• With my 27" External screen configured as primary monitor (DPR ratio = 1.5 ) I get a pointSizeF value of 8

According to QT doc, I would expect to always get the same value as pointSizeF() is supposed to be device independent.