During configure phase qt5compat is reported to be missing and GUI will not work: ... checking for Qt6Core Qt6Widgets Qt6Gui Qt6Qml Qt6QmlModels Qt6QmlWorkerScript Qt6Quick Qt6QuickControls2 Qt6QuickLayouts Qt6QuickTemplates2 Qt6Svg >= 6.2... yes checking for Qt6WaylandClient >= 6.2... no checking if contribs provide target_qt.conf... no checking for qmake6... /usr/lib64/qt6/bin/qmake6 checking for moc... /usr/lib64/qt6/libexec/moc checking for rcc... /usr/lib64/qt6/libexec/rcc checking for uic... /usr/lib64/qt6/libexec/uic checking for qsb... /usr/lib64/qt6/bin/qsb checking for qmlcachegen... /usr/lib64/qt6/libexec/qmlcachegen checking for python3... python3 checking if required Qt plugins are installed with /usr/lib64/qt6/bin/qmake6 and conf ... checking for QtQml.Models ... yes checking for QtQml.WorkerScript ... yes checking for QtQuick.Layouts ... yes checking for QtQuick.Window ... yes checking for QtQuick.Controls ... yes checking for Qt5Compat.GraphicalEffects ... no no configure: WARNING: qt runtime dependencies are missing, disabling qt interface ... Manually installing dev-qt/qt5compat fixes the issue.
Run in the same issue, but the qt5compat was installed on my system. I was needed to recompile qt5compat with USE=qml enabled. dev-qt/qt5compat[qml] should be the missed dependency in ebuild
*** Bug 933556 has been marked as a duplicate of this bug. ***