I hear you, I ran into this issue too, it’s definitely a pain point. The only way to get around this at the moment is to use a global variable.
Any element on the canvas can change the value of a global variable, and this variable in turn can be used to control the state of any other element (no parent-child connection is necessary between the elements). I’m not sure if I can explain it very well, but here’s a good demo from Figma on how you can achieve this: Figma tutorial: Prototype with variables - YouTube .
Consider how the global “hasCart” variable is used in the demo to connect the “Add to cart” and the “Basket” buttons to each other, even though they are completely unrelated components. In the same way, you could set an interaction on your dropdown component (_Struktur-Mehr An…) to set a global variable, and link the value of that variable to the visibility of the variants in your form component (Kundeneingabe-Felder-Layout-Variaten).
Hope this helps you! 