When try to run the declarative camera example on a android.
I'm getting an error:

W Gralloc3: mapper 3.x is not supported
W libdeclarative-camera_arm64-v8a.so: qrc:/declarative-camera.qml:52:1: module "QtMultimedia" plugin "qtmultimediaplugin" not found
W libdeclarative-camera_arm64-v8a.so: import QtMultimedia
W libdeclarative-camera_arm64-v8a.so: ^

gallery_controls2 example:

W Gralloc3: mapper 3.x is not supported
W Gallery : QQmlApplicationEngine failed to load component
W Gallery : qrc:/gallery.qml:53:1: module "QtQuick.Controls" plugin "qtquickcontrols2plugin" not found

I have installed everything on the clean Ubuntu as written here:
https://wiki.qt.io/Building_Qt_5_from_Git

I have build Qt6 (dev) on android as below:

git clone ssh://codereview.qt-project.org/qt/qtbase
git clone ssh://codereview.qt-project.org/qt/qtshadertools
git clone ssh://codereview.qt-project.org/qt/qtdeclarative
git clone ssh://codereview.qt-project.org/qt/qtmultimedia

• • • • Host Side ****
        qtbase:
        ...
        ../../qt6/qtbase/configure -nomake tests -nomake examples -no-warnings-are-errors -opensource -confirm-license -developer-build
        cmake --build . --parallel $(nproc)
        ...
        qtshadertools, qtdeclarative and qtmultimedia:
        ...
        ../../qt6/qtbase/bin/qt-configure-module ../../qt6/qtshadertools
        cmake --build . --parallel $(nproc)
        ...
      • Host Side ****

• • • • Android Side ****
        ...
        ../../qt6/qtbase/configure -xplatform android-clang -nomake tests -nomake examples -android-ndk $ANDROID_NDK -android-sdk $ANDROID_SDK -qt-host-path ~/dev_qt6_v7/qt6_build_host/qtbase -android-abis arm64-v8a -developer-build -no-warnings-are-errors -opensource -confirm-license
        ...
        ../qtbase/bin/qt-configure-module ../../qt6/qtshadertools
        cmake --build . --parallel $(nproc)
        ...
      • Android Side ****

The Declarative camera example works on the host side(Ubuntu 20.04).

Other examples works also on the Android side also.

Everything has been checked that everything should be fine.