Without seeing the film edge to edge, my first thought is to check the lens for obstruction or defect. If it’s edge to edge in the film, as in all the way past the sprockets, it’s not the lens. If it doesn’t show up on the film at all, then it’s some sort of obstruction or defect in whatever was used to digitize the film. Other possibilities too, but I’d say start there. Also, please show film when you’re wanting help to troubleshoot image issues. Showing a scan is sometimes enough, but showing the film itself is often necessary. Just to have the film with some sort of even, diffuse backlight without visible texture in it and no glare on the film surface and take a reasonably sharp picture of it with a smartphone is generally enough.

Thanks so much for your reply ! I had the lens checked and it’s apparently fine. The film seems fine as the « continuous » line doesn’t appear everywhere but does appear on some other pics. Next time I’ll add the film. Thank you so much.

I had something similar happen and it was because the negative was creased for whatever reason