Random banding with 5D classic

Looking at my images I am seeing occasional banding with my normal processing using Lightroom. I believe that once in a while I may see it in the LCD before it gets processed, but I can't confirm that right now.

These two images were taken within seconds of each other (different focus points) - but one has banding and one does not. Does anyone know what this banding is coming from?

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Electronic interference from triggers maybe?

+1 Are you using some kind of trigger for your lights?

No lights were used at all, no flashes, no triggers, no nothing. No IS either.

That is weird. Cool shot, btw.

Not too sure what you are seeing. I see noise/artifacting in both images.

diagonal bands in the midtones and shadows. Very obvious IMO.

I think I see what you mean. In this direction / , correct? Seems to be covering the entire picture. Hard to see it at first.

Is this perhaps related to the diagonal bokeh people are seeing with certain lenses and filters?

Did you have a UV filter atached?

I don't use filters, and there were no flashes, triggers, or anything else attached to the camera except the lens (24L II). No battery grip, just the base camera.