[REG 6.1.0 -> 6.2] No TLS backend available in statically built project

1. Have a statically linked Qt.
   I configured and built it with:

   /tmp/cmake-network/qt5/configure -static -release -prefix $PWD/qtbase -opensource -confirm-license -nomake tests -nomake examples && cmake --build . --parallel
   

2. Use this to build the attached cmake project:

   /tmp/cmake-network/static/qtbase/bin/qt-cmake /tmp/report/ && cmake --build .
   

3. Run the resulting binary passing the attached certificate file:

   ./pem /tmp/report/qt-io.pem
   

   You will get output like:

   qt.network.ssl: No functional TLS backend was found
   qt.network.ssl: No functional TLS backend was found
   qt.network.ssl: No TLS backend is available
   qt.network.ssl: No functional TLS backend was found
   isNull(): true
   expiryDate(): QDateTime(Invalid)
   

Doing exactly the same with a non-static build of Qt will result in the output:

isNull(): false
expiryDate(): QDateTime(2021-09-29 12:00:00.000 UTC Qt::UTC)

I expect the same output from a static build.

Should my CMakeLists.txt contain a mistake which causes this, please let me know.