[Reg 5.15.3->6.0] Dialog buttons translated even though they shouldn't be

Prerequisite: Have English and German as "preferred languages" in System Preferences > Language & Region, make sure English is on top and "Primary".

Open Designer, create a form, drag some widget on it and close Designer. A dialog pops up, asking what to do with the modified document. Even though Designer is completely in english (as it should), the dialog buttons are in german.

The same is the case with the dialogs in the Qt Quick Controls Gallery example.

The situation is similar to QTBUG-87858 , but limited to a specific kind of buttons. I could not reproduce with the Standard Dialogs example.