Streak/creases marks on negative

Hi everyone,
So I shot a roll of pancro 400 with my rolleiflex about a month ago. I just finished the roll about a week ago and sent it to a local lab to be developed and scanned. The last 6 frames of the negative ended up showing these small streaks/creases on them. Does anyone know what might have caused this?

This looks like uneven development to me.

And the streaks are on the negative, not just on the scan?

Yes, it’s on the negative as well.
I might have found the culprit. These streaks may have been caused by the film sticking to the backing paper. If you look at the backing paper, you’ll see the same patterns on the negative. It’s quite humid where I live, and I just left the film in the open before using it, so that might be the cause.

possibly, the month that the film has been sitting around before finishing it, might be a contributing factor. On the other hand, film is usually rolled up fairly tightly so that humidity should not be able to get in between the film and its protective paper. Nevertheless, it looks like the paper has left its marks.

Have you checked the light seals of the camera? Seals can deteriorate with time, although older cameras used felt instead of the polyurethane seals, which get gooey after a few years. New seals might help to keep the climate out - if the inside can be kept or made dry before the film is inserted.

The culprit is probably the backing paper and the humidity. Imho the only solution is to try to re-wash ( 5 to 10 minutes ) the film with a good wetting agent and before drying to wipe both sides of the film gently with a very soft sponge.