This PR is a follow up of #23489.
The initial support of macOS Big Sur by Qt was pretty broken. Fixup commits were submitted into the dev
branch, and backported to 5.12
and 5.15
branches.
Those fixups were released with the Qt 5.12.11, but, unfortunately, will be never (?) released as Qt 5.15.3 (for license issues, I guess).
Therefore, bumping Qt version from 5.12.11 to 5.15.2 brings a regression into rendering of some widgets in macOS BigSur.
This PR fixes this regression.
See:
- bitcoin/bitcoin#22054
- https://bugreports.qt.io/browse/QTBUG-86513