Your camera chamber is contaminated with clouds of developer dust? Hmm.
... OR ... Check very carefully any areas of the film outside of the images that are a little gray or a lot gray but not black. For example if the leader black shades to gray over the space of a few millimeters, check there very carefully to see if there are spots. And check any pressure streaks or crimp fog or light fog and check at the edges of the numbers and edge markings.
If the dots are not in any unexposed areas, then it is very localized over development of silver.
Are there clouds of developer dust in the darkroom air? Unlikely.
Check the developer to see if it is perfectly clear or if there is sediment that gets stirred up or specks that are suspended almost colloidally. Also, check the developer after it is fully diluted, too.
My first post, way back at the start should have been
"This look like light scatter in Pinhole photography, was this a pinhole?"
I thought it, and should have added it to my questions of processing. When I was doing a lot of pinhole I saw them all the time. Even in when not pointed at a strong light source.
One thing maybe to prove this to you is that you can find the same pattern on different frames. Now one roll may not be enough to see, But on the hundreds of pinhole frames I have done I could see similar patters of black spots.
D-76 is a standard developer, although not one I use.
Ansel Adams - The Negative