Graphical Error on older iOS Companion App

My Statusdisplay is an older iPad Mini 4 with iOS 15.8.7
Since this Month I have an graphical error on the Dashboard:
The Top Line with the different dashboards is showing a empty row above.


In developer mode in Browser, everything is fine as well as on an other iPad, in Android App etc.
Just on this one Device.
Already cleaned the cache, reset and reinstalled the app, updated iOS…
Any idea about this?