Developer Fault or Digitizing Fault?

I’m getting strange dark but faint lines through my images. In the images below you can see them running horizontally across the sky in the image (from 6x9 folder). I can see them in film shot with different cameras as well (can only attach one image) so it’s not the camera itself.
I’m guessing the streaks are from developing? I can’t really see the streaks in the unconverted negatives, even when using a loupe. But, since they’re faint that may not be surprising given the density of the negatives.
All images ‘scanned’ with Olympus E-M1ii and Oly 60mm macro, then converted with NLP 2.1. I even changed the orientation of light source (Iphone 11) to make sure it wasn’t some weird interference from that.
Negative is held a couple of inches above the phone when digitizing.
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Here’s a scan of a neg shot with Fuji 645 and you can see the streaks running vertically (the 645 orients the image differently on the negative–portrait instead of landscape). The splotches lead me to think perhaps some careless developing?

The lines run in the direction of transport, be it during manufacture, during film transport in the camera or during development - or by the backlight.

Do you get the same lines when yo digitize the same negatives again using a different light source?

Light source is Iphone 11 max pro. The film is elevated off the surface a couple of inches. I have not tried a difference light source. However, I have changed the orientation of the Iphone by 90 degrees and no difference in the lines. I’ve tried diffusing it with some dura-lar paper. Same result. So, I don’t think it’s a light source issue.

If these lines are only present in a few images, I’d try to fix them with Lightroom’s healing tool…