Yes, more details are needed. Dimensions such as pinhole to film distance and film size, etc. Is the pinhole in paper-thin material? I've never tried a pinhole in a thick sheet, but those look like what I might expect if I drilled a small hole through a thick piece of stock.
It is surprising how easily vignetting can occur, especially if the camera is set up for a wide angle of view.
(Been there, done that, etc.)