Paper Inclusions Or Foxing?

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I often come across MNH OG stamps that have the small bits in the gum that the attached image shows.

I've tried, but have never been able to a satifactory conclusion, to find information one way or the other on whether these are harmless inclusions, or dangerous fungal matter.

Up to now I never store anything with even one of these marks near any of my other stamps because I worry that if it's a fungus that could spread. But I'd like to try to get a handle on what the actual fact is for these bits.

The thing that I notice most is that the bits are pretty solid and crisp with no halo around them, they don't seem to be in clusters, and the stamps themselves are in excellent condition with no sign of any mildew, etc. Some are clearly ink color (reds, blues) so I assume they are just ink from a stamp that was under the stamp.

I want to believe they are just harmless inclusions, but I'm still concerned that I could infect my other stamps. The stamps in the image are 1200 DPI scans from 1960s MNH OG stamps that look superb (except for the gum-side black inclusions).

Thanks for any ideas you can share!

I don't think it's foxing. Under heavy magnification, foxing looks like ear wax.

What stamps are we talking about? The gum itself is terribly dried out.

The stamps are Greek from 1966. They are in superb, very fresh condition except for the spots and that the gum is a little dry. I don't see any evidence of mildew or stains or anything else so I wonder if the bits/spots are just some inclusions and not foxing? But I still will not put them with my other stamps unless I can be sure it's an inclusion and not fungal/foxing.