WASM build broken on 6.5 (missing Qt6::qtprotobufgen)

#24 81.07 -- Configuring submodule 'qtgrpc'
#24 81.21 CMake Error at qtbase/cmake/QtToolHelpers.cmake:605 (message):
#24 81.21   Failed to find the host tool "Qt6::qtprotobufgen".  It is part of the
#24 81.21   Qt6ProtobufTools package, but the package could not be found.  Make sure
#24 81.21   you have built and installed the host Protobuf module, which will ensure
#24 81.21   the creation of the Qt6ProtobufTools package.
#24 81.21 Call Stack (most recent call first):
#24 81.21   qtbase/cmake/QtToolHelpers.cmake:55 (qt_internal_find_tool)
#24 81.21   qtgrpc/src/tools/qtprotobufgen/CMakeLists.txt:5 (qt_internal_add_tool)
#24 81.21
#24 81.21
#24 81.21 -- Could NOT find Qt6ProtobufTools (missing: Qt6ProtobufTools_DIR)
#24 81.23 -- Configuring incomplete, errors occurred!
#24 81.23 See also "/development/qt5_build/CMakeFiles/CMakeOutput.log".
#24 81.23 See also "/development/qt5_build/CMakeFiles/CMakeError.log".
#24 81.38 CMake Error at /development/qt5/qtbase/cmake/QtProcessConfigureArgs.cmake:987 (message):
#24 81.38   CMake exited with code 1.
#24 81.38
#24 81.38
------
executor failed running [/bin/sh -c /development/qt5/configure -qt-host-path /usr/local/Qt-x64 -xplatform wasm-emscripten -nomake examples -prefix /usr/local/Qt-wasm]: exit code: 1

# Based on https://github.com/emscripten-core/emsdk/tree/master/docker
FROM emscripten/emsdk:3.1.27

RUN mkdir -p /development

# Install Mesa OpenGL (needed to build Qt for x64)
RUN apt-get update && apt-get -y install mesa-common-dev libgl1-mesa-dev libglu1-mesa-dev

# Clone Qt sources
WORKDIR /development
RUN git clone --branch=6.5 https://code.qt.io/qt/qt5.git
WORKDIR /development/qt5
RUN ./init-repository

# Build Qt for x64 (disable parallelization to debug build failure)
RUN mkdir -p /development/qt5_build_x64
WORKDIR /development/qt5_build_x64
RUN /development/qt5/configure -nomake examples -nomake tests -prefix /usr/local/Qt-x64
RUN cmake --build . --parallel 1
RUN cmake --install .

# Build Qt for WASM (disable parallelization to debug build failure)
RUN mkdir -p /development/qt5_build
WORKDIR /development/qt5_build
RUN /development/qt5/configure -qt-host-path /usr/local/Qt-x64 -xplatform wasm-emscripten -nomake examples -prefix /usr/local/Qt-wasm
RUN cmake --build . --parallel 1
RUN cmake --install .