Dropdown Icons in mobile menu

Hi there,

I have a display problem with the mobile menu. The first level shows some strange double triangles („ÜBER UNS“ at the attached screenshot). The third level arrows are displayed correctly as you can see at e.g. „Einsatzmannschaft“ and below.

Do you have any idea how to fix it?

URL is: https://feuerwehrwoerth.de

Thanks in advance!