After upgrade to LM 21.3 the theme doesn't work properly for a Qt-app

[Dan-cer]

I have been using the small German address book app Easykontakt for years. It is written in Qt4 and Qt5 and was also very compatible with this theme - cinnamox. After upgrading to 21.3 this has changed. The program has the theme color in some areas, in others it remains white, and the font in the list is black on a dark background.

Is there a way to correct this? So far I have only found the Qt5 settings of LM. There would be a solution there if this gtk theme was omitted, but I would like to keep it.

Thanks in advance and thanks again for this nice topic!