Right. I sent an email to the support with 3 resized screenshots from the default version of the DKS and 3 resized screenshots after the latest patch. I also included the report.xml from the support tool. Screenshots were originally 1920*1080, but i resized them by half to keep email size reasonable. The issue should still be visible though.
Edit: I think i have solved my issue. Turns out, that a custom 4:3 resolution (1440*1080) i had made in the Nvidia control panel fooled the game into thinking it has to run at that exact resolution regardless of the fact, that i had selected 1920*1080 in the menu. After deleting the resolution in the Nvidia cp the game looks normal.
Edit2: Yep, that's it. I tried creating the resolution again, and i can reproduce this. When there is no custom resolution in the Nvidia control panel, the game looks normal, but as soon as i make 1440*1080, the game looks stretched.