I'm brand new to film photography and I just took my first rolls to a local shop today. The first half of the roll had these horizontal lines at the top and the second half was fine. Is this a film issue or a development or scan issue?
Considering that the mark is in the exact same position, I would suspect of the camera in the first place (I'm assuming the marks are present in your negatives). I have experienced some similar issue with my fathers Zeiss Ikon back when I began taking shots on film age. In my case what caused that was some light leakage which I discovered after checking every joint and slots against some strong light. I would recomend you check the camera for posible parts with this kind of light leakage. The light leakage may also happen in the film reel in some extreme conditions or in cases where it was manually reloaded.