It is also conceivable that the hinge straps have the wrong bend. 109336 has a 0 mm bend and should look like on p. 8 and not like on p. 15 in step 4. That looks more like 109338.
So I had to realize that my father had indeed assembled the shelf incorrectly; now I have fixed it and the door situation is fine. I would like to apologize for the effort you made to help me and at the same time, of course, thank you.