QLineEdit's clear button appears pixelated when higher than normal

--Steps to reproduce:

1. Create a simple QLineEdit with clear button enabled.
2. Manually increase its height
3. The clear button appears big and pixelated.

It can also happen when the user increases the font size of the QLineEdit, since then the height also increases.

--Expected behaviour:

Clear button should appear sharper and perhaps not so big.

It may be related to https://bugreports.qt.io/browse/QTBUG-39517