In a default Trisquel installation, QT apps do not follow MATE font and scaling settings
In a default Trisquel installation, in QT apps, e.g. KeypassXC, Quassel, fonts are not modified when modifying the fonts in the MATE settings. Same problem for scaling. Installing qt5-gtk-platformtheme solves the problem. Suggestion: add it to some meta package (not sure which one).