Text rendering artifacts in QWebEngineView with custom high DPI rounding policy

This is an odd bug that got my attention in 6.4.1 but I am sure I noticed it on 6.4.0 as well (can't test it at the moment). It does not appear on 6.3.2. 

If you set setHighDpiScaleFactorRoundingPolicy() to something like Qt::HighDpiScaleFactorRoundingPolicy::Round (for instance to avoid the known rendering artifacts with scaling factors like 125%), the text in a web view will look jagged or somehow in low quality.

Selecting the text (which should cause a repaint) will not change things but moving (not even resizing, just moving) the window will make the text clear again.

Problem only occurs on 6.4.x and with a custom high DPI rounding policy - other widgets, including QTextEdit, look fine.

I could not find any existing issue mentioning this so I hope it's not a duplicate.

The attached sample application simply contains a QWebEngineView and sets the rounding policy to reproduce the bug.