At 17mm, central sharpness is outstanding from f/2.8 through to f/8, excellent at f/11, very good at f/16 and good at f/22. The edges are excellent at f/2.8, outstanding at f/4, excellent at f/5.6 ...

This is something that this lens has in common with some other Nikon Z optics, so it seems to be a design choice. It can of course be handled in camera or in software, or we can exploit it ...