Compiling SQL Driver Plugin with QMake not working anymore

Since I installed Qt 6.5.0 (because of bug QTBUG-113612), I can't compile another project anymore: an sqlite plugin that supports encryption of the database.

load(qt_plugin) in qsqlite-aes.pro gives an error: "cannot find feature qt_plugin".

Compiling the project results in:

Undefined symbols for architecture arm64:
  "_main", referenced from:
     implicit entry/start for main executable
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [qsqlite-aes_6_5_1.app/Contents/MacOS/qsqlite-aes_6_5_1] Error 1
17:02:56: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project qsqlite-aes (kit: Qt 6.5.1 for macOS)
The kit Qt 6.5.1 for macOS has configuration issues which might be the root cause for this problem.
When executing step "Make"