Skoda Octavia III + Dynavin D9 Radio: What is this cable?

Dear community! I replaced the original radio (Bolero, I assume) in my 2016 Skoda Octavia III 5E with a Dynavin D9-7. Everything works perfectly, but I'm not sure about one connection: 1) whether it's correct and 2) even necessary. I've already received two different answers, so I'm asking here—maybe someone knows more! When you remove…