UV Unwrapping is messed up because of a vertex leading into the wrong ending my UV Unwrapping is messed up because of a vertex that leads into the wrong ending creating a triangular face (which is not the best thing, as I followed some tutorials saying it). (I think thats the problem)
So the top left line should lead into a new vertex and not the same as the top right one.
Thanks in advance!!
I try to showcase it in the following Images:
Yes that is your problem and you can fix it by selecting the stray edge in Edge mode and dissolving it by pressing x and by selecting Dissolve Edges.

Next use knife tool k and draw the missing edges.


Accept the cut by pressing Enter.
Last select the newly created vertices and move them to better location by double pressing g and sliding them closer to the edge.