Photography

Cheap prints. :)

The pink dots are probably from improper washing from the photo developer. It takes a while for the results to show up. If it was from exposure to sunlight, the color fade would be more consistent across the whole print.

Printed photos aren't necessarily stable for an indefinite period of time.

Afaik, degradation can be due to residual printing chemicals like fix not having been fully removed from the paper, for example if not washed for long enough after processing.

Making archival prints includes some additional steps to reduce the risk of residual chemicals causing degradation later, but something like a 1hr photo place probably isn't taking those steps.

If you still have the negatives, the best thing to do would just be to get some reprints made from those.

If you still have the negatives, get them scanned.

If you don't have those negatives anymore, get your photos scanned asap and retouched to remove those defects. Some could be easy to remove, some could be a bit more challenging depending on the location in a picture (removing a red dot in a blue sky is way easier than removing those on complex structures).

It could be chemicals not washed out during development (as someone else already mentioned), could also be dust particles (like some chemicals in powder form, concrete dust, ...) in combination with high humidity.

If you print images to have them last long (really long like tens of decades) have them printed with Canon or Epson fine art peinters on high end papers. Chemically developed prints will fade way faster. (source: Wilhelm Image Research)

Cosmic rays ?

Looks moisture to me. Like there were hit with drops of liquid.

Bad chemistry would have the prints fade evenly. Not in little spots like that.

Those were not washed properly and chemistry was left on the surface of the photos.

pink (kodak/lucky) or light blue (fujifilm) is the color of undeveloped emulsion. The photo paper is starting to break down. Was it a bad wash? Possible but not likely. Bad color developer? Possible but there would be streaking and not so much spotting. It's more like a bad batch of photo paper. Scan from negatives to reprint your photos is the best option.

The other (remote) possibility is degration from reflected sunlight or ultraviolet light, like through crystals or glass at an opaque angle that dispurses the light.