Okay got it. Still not sure what to think about those messages put in front so prominent - makes me personally feel a bit uncomfortable tbh. Maybe I just need to get used to this UI change and learn to safely ignore those warnings… which also is not a good behavior I think 
Meanwhile there are even more warnings I need to (should I?) take a look at.
Anyway: what is that 4th option -> it is the bind option one below the current respond one I guess. Doesn‘t sound like something I‘m looking for according to the docs https://docs.pi-hole.net/ftldns/interfaces/:
About the only time when this is useful is when running another nameserver on the same port on the same machine. This may also happen if you run a virtualization API such as
libvirt.
Man DNS has become quite complicated. Props to all you guys mastering all that technical details 
For now I think I‘ll start living with and probably ignoring those warnings. As you said - they‘ve always been there and things are working fine anyway.
Thanks for explanations - and merry x-mas