Thank you both very much for the replies.
I just have the Kit lens "NIKKOR Z DX 18–140 mm 1:3,5–6,3 VR". It was on sale and I wanted something light, that can be used as a single "all-purpose" lens when I'm traveling.
On my previous cameras, I always thought that I have a very good hand for focusing manually. However, that doesn't seem to be true with this lens. I have no feel for the manual focus at all. I think it's far too sensitive for me and even a fracture of a degree seems to make such a huge difference. I think, I will need much more training before I will be able to use the manual focus of this lens.
… or switch focus peaking on.
Custom function d9, page 370 in the reference handbook.
It really is a gamechanger.