I would advise against noise it almost always just makes the image look worse instead of giving any practical effect. For when it’s supposed to be a poster I’d say make some deep cuts in it, bend a corner, perhaps a burn mark and make it look like it was folded at some point. You know like when you unfold a note you had for ages in your pockets on the fold lines the color is also gone and maybe it also comes loose at these points.
On another note it still looks too “high res” for pixel art. Actual pixel art is like really blocky like a video game from the 80s or something. Also the German doesn’t sound right, it reads like something from google translate.