Why is there so much vignette on my new lens?

Hey all, I'm just starting out in the world of photography and was hoping you great folks could help me. I got a Nikon ZF as my first camera and it works great with the 49mm Nikkor lens I got. No issues there. My problem is that I bought the TTArtisans 25mm f/2 and it just has so much vignette it's crazy. I read reviews saying it had *some* vignette, which I felt I could crop out. But the amount that is actually there is very distracting. I added a couple of my test shots as examples.

Is this just how the lens is? Did I get a dud? Or am I doing something wrong and need to adjust a setting?

I really appreciate any help you guys can give. Thanks a ton in advance.