u/Ok-Zookeepergame8335

Dear all, I have troubles with some of my closed polysurfaces, that are showing wrong shadings. It looks like a bug, but also shows up when I render it. I build it by cutting two extrusions and then offsetting the surface, when it showed up. I noticed something similar after a boolean cut once. I also tried exporting the part in a seperate file and it still showes up. Is this problem known/did anyone ever have it? Thank you in advance!