On Android, I think it's just a hardcoded prioritized list and then alphabetical for the rest of the fonts. For example Chinese will be always preferred over Japanese if the default fonts cannot handle Japanese correctly. So it is possible that this could be improved to prefer locale-fonts first.

This issue can be reproduced by displaying some characters affected by Han-unification problem. For example, QString("\u76f4\u7dda") can be displayed in either Chinese or Japanese because the Unicode supports both variants. But on Android, it is displayed in Chinese whatsoever, regardless of, for example, QLocale settings or OS language settings.

Issue is not repro on Android 9, but on Android 11 it is on Qt 5.15.9. With Qt 5.15.3 it is not repro