Yocto 4.0: meta-qt6 QtWebEngine 6.2.4 could not find Qt6Config.cmake

sonic74

Hello,
I successfully built meta-qt5 with Yocto 4.0 under Ubuntu 20.04.5
Then I tried to upgrade to meta-qt6 (branch 6.2.4), which also builds fine - except for qtwebengine. This fails suddenly with

| FAILED: src/host/src/hostBuild-stamp/hostBuild-configure /mnt/chromium/fsl-community-bsp/build-x11-qt6/tmp/work/cortexa9t2hf-neon-imx-fslc-linux-gnueabi/qtwebengine/6.2.4-r0/build/src/host/src/hostBuild-stamp/hostBuild-configure
| cd /mnt/chromium/fsl-community-bsp/build-x11-qt6/tmp/work/cortexa9t2hf-neon-imx-fslc-linux-gnueabi/qtwebengine/6.2.4-r0/build/src/host && /mnt/chromium/fsl-community-bsp/build-x11-qt6/tmp/work/cortexa9t2hf-neon-imx-fslc-linux-gnueabi/qtwebengine/6.2.4-r0/recipe-sysroot-native/usr/bin/cmake -DCMAKE_TOOLCHAIN_FILE=/mnt/chromium/fsl-community-bsp/build-x11-qt6/tmp/work/cortexa9t2hf-neon-imx-fslc-linux-gnueabi/qtwebengine/6.2.4-r0/recipe-sysroot-native/usr/lib/cmake/Qt6/qt.toolchain.cmake -DWEBENGINE_ROOT_BUILD_DIR=/mnt/chromium/fsl-community-bsp/build-x11-qt6/tmp/work/cortexa9t2hf-neon-imx-fslc-linux-gnueabi/qtwebengine/6.2.4-r0/build -DWEBENGINE_ROOT_SOURCE_DIR=/mnt/chromium/fsl-community-bsp/build-x11-qt6/tmp/work/cortexa9t2hf-neon-imx-fslc-linux-gnueabi/qtwebengine/6.2.4-r0/git -DGN_TARGET_CPU=arm -DCMAKE_C_FLAGS= -DCMAKE_CXX_FLAGS= -DQT_FEATURE_qtwebengine_build=ON -DQT_FEATURE_qtpdf_build=OFF -GNinja /mnt/chromium/fsl-community-bsp/build-x11-qt6/tmp/work/cortexa9t2hf-neon-imx-fslc-linux-gnueabi/qtwebengine/6.2.4-r0/git/src/host && /mnt/chromium/fsl-community-bsp/build-x11-qt6/tmp/work/cortexa9t2hf-neon-imx-fslc-linux-gnueabi/qtwebengine/6.2.4-r0/recipe-sysroot-native/usr/bin/cmake -E touch /mnt/chromium/fsl-community-bsp/build-x11-qt6/tmp/work/cortexa9t2hf-neon-imx-fslc-linux-gnueabi/qtwebengine/6.2.4-r0/build/src/host/src/hostBuild-stamp/hostBuild-configure
| Re-run cmake no build system arguments
| CMake Error at CMakeLists.txt:19 (find_package):
|   Could not find a package configuration file provided by "Qt6" (requested
|   version 6.2.4) with any of the following names:
|
|     Qt6Config.cmake
|     qt6-config.cmake
|
|   Add the installation prefix of "Qt6" to CMAKE_PREFIX_PATH or set "Qt6_DIR"
|   to a directory containing one of the above files.  If "Qt6" provides a
|   separate development package or SDK, be sure it has been installed.
|
|
| -- Configuring incomplete, errors occurred!

What could be the problem?
6.4 works (after adding cups to DEPENDS)