zoom – Why does an underexposed "shadow" appear along the edge of a 35mm film when using my 70-210mm lens?

I've taken a few rolls on Minolta XG-M with different lenses and some images have an underexposed edge. It takes a while for me to go through a part until I forget which lens / settings I used. But when I look through the pictures, I'm pretty confident

  1. The shaded area is displayed on the same page.
  2. It only appears when I use my Vivitar 70-210mm.

That pretty much excludes shutter problems, I guess.
Could it be the lack of a lens hood?

Here are some examples:

example 1
Example 2
Example 3

TO EDIT:
Sorry for the mistake, the lens is a Sigma Zoom-k II f / 4.5 70-210 mm Multi Coated Lens. Other lenses I use are Minolta MD 50 mm 1: 1.7 and Minolta MD Zoom 24 – 35 mm 1: 3.5, which do not seem to have this problem (which reminds me of the pictures taken).
The zoom lens shows some dust, but looks good otherwise. You are not sure how to test the interaction between the iris and a mirror.
I also scan with a DSLR + zoom reverser, so I had to improvise with these pictures, but the same hue does not seem to overlap with two frames:

requested example 1requested example 2