Incorrect toolbar button size with style "Fusion" and font-size 13pt

When mac application has style "Fusion" and font-size 13pt, toolbar buttons(at least) a little bit smaller than they are supposed to be, and button text is cut.

Minimal reproducible example:

#include <QApplication>
#include <QMainWindow>
#include <QStyleFactory>
#include <QToolBar>
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QApplication::setStyle(QStyleFactory::create("Fusion"));
    a.setStyleSheet("* {font-size:13pt}");
    QMainWindow w;
    QToolBar *toolbar = w.addToolBar("toolbar");
    toolbar->addAction("Hello, Cruel World!");
    w.show();
    return a.exec();
}

The bug appears only on macOS, only with style "Fusion" and only with font-size 13pt. I attached several screenshots:

fail_fusion_13.png - the bug. Style "Fusion", font-size 13pt
ok_default_13.png - expected behavior. Default style, font-size 13pt
ok_fusion_14.png - expected behavior. Style "Fusion", font-size 14pt

My system:

$ uname -a
Darwin MacBook-Pro.local 19.5.0 Darwin Kernel Version 19.5.0: Tue May 26 20:41:44 PDT 2020; root:xnu-6153.121.2~2/RELEASE_X86_64 x86_64

Maybe there is a workaround for this? Apart of setting different font size or style, of course.