Blurry checkboxes on Mac OS

In Mac style QCheckBox-es with attribute Qt::WA_MacSmallSize set are blurred and shifted by 1 px vertically. Please see the attachments for comparison between Qt 5.4.1 (correctly drawn) and 5.15.1 (incorrect).

The problem is caused by the following code in qmacstyle_mac.mm:

const auto vOffset = [=]

{ // As measured if (cs == QStyleHelper::SizeMini) return ct == QMacStylePrivate::Button_CheckBox ? -0.5 : 0.5; return cs == QStyleHelper::SizeSmall ? 0.5 : 0.0; }

();

Setting vOffset to 0.0 fixes the issue.