Hi Russell, I have no clear idea what is causing the beahviour you're seeing.
Let me add, I have the feeling that this is better reported upstream rather than to another Debian maintainer. I'd go with an issue targeting the plasma-mobile team [1], hopefully they'll know how to proceed with this. But of course, feel free to reassign this to another Debian package. Kind regards Marco [1]https://invent.kde.org/teams/plasma-mobile/issues/-/issues