I don't think the app changes the default font size for menus, unless you set "Set colors for tabs, tool bar and menus" is set in Appearance config tab and also modify "menu_css" manually (or CSS stylesheets that come with the app).
To change the menu font size: click "Edit Theme" in the Appearance tab and add ";font-size: 12pt" to "menu_css".
I wonder if this could be something related to newer versions of Qt GUI framework. It should be possible to set some DPI-related environment variables for Qt to scale up the UI (for example "QT_SCALE_FACTOR=2"). Some details here:
https://doc.qt.io/qt-6/highdpi.html