NEED HELP Why is my model behaving like this?

Hello guys, I wonder why my model is bevaing like this… I subdivided it, added a subdivision surface, made it smooth shading and everything like that but now I get these black fuck things in the corner and stuff like that, any idea of what it could be?

You’ve split the edge with the edge split modifier. Look the change the split angle or mark selected edges as sharp and just use the sharp edges option

Crease the edges that you want sharp. (Ctrl-E, Edge Crease, 1.0) That will keep the Subdivision modifier from pulling those edges away from the splits.