There are no physical scratches, and the odd marks running along the length of the film, but only periodically, with other images good, negates the film being scratched in the bulk loader or the camera. It probably does not relate to problems in the developing chemistry itself. We do not know what kind of processing tank was used.
My ideas in no order suggesting relative probability:
1. An intermittent light leak during the bulk film loading process, light filtering through the light trap. Some loaders do not have a positive lock on the door covering the cartridge.
2. If developed with a rotary processor, like a Jobo unit, some mechanical failure of the processor & drum causing inadequate delivery of fresh developer to film.
3. Manufacturing flaw in the bulk film roll.
It's a real puzzle.