This change seems to break all plugin loading for us, under Q_OS_ANDROID:

commit ec0e9f29dfd0b45edf5fd33e8ccf763e604612d7 
Author: BogDan Vatra <bogdan@kde.org> 
Date:   Tue Sep 17 09:54:28 2019 +0300

It removes the plugin path suffixes, so all plugins are expected to be under `QT_PLUGIN_PATH` directly (i.e. doesn't look in platforms/, and other subfolders). It also seems to assume plugin names start with `libplugins_*`, which isn't the case. There are other parts of the patch that we also had to remove, as they introduced dependencies to code that wasn't built. E.g., `QtAndroidPrivate::javaVM()` is used under `Q_OS_ANDROID`, but it seems it isn't even compiled for embedded android :

android:!android-embedded { 
        SOURCES += \ 
                   kernel/qjnionload.cpp \ 
                   kernel/qjnihelpers.cpp \ 
                   kernel/qjni.cpp 
        HEADERS += \ 
                   kernel/qjnihelpers_p.h \ 
                   kernel/qjni_p.h 
}

We had to revert this patch to get to 5.14, not sure what the idea was . Maybe it should have been Android (not embedded / headless Android) only.