We could, but… Qt 5 will not have a public release for all practical purposes. The Qt Company, in their infinite stupidity and cupidity have decided to only make available Qt5 releases to the public as free software one year after the release. So if we report a bug, and if it gets fixed, which is not at all likely, we won’t get the fix. Which in turn makes me disinclined to report bugs to them.
We see a similar issue with Qt 5.15 and resizing brushes, by the way.
We’re really on the horns of a dilemma here: for our own builds, we use a heavily patched Qt 5.12 because newer versions of Qt have killer bugs (like breaking multi-window mode on Windows). If we investigate this issue and find a fix, it’ll be a Qt 5.15 fix, but we cannot ship with Qt 5.15 anyway because of all the other bugs.
And in the meantime, Qt6 is out, with a metric ton of bugs, a bunch of modules missing and some really dubious design choices, like removing support for Angle on Windows.
Sorry for the rant… This really is quite some problem.