'Corroded' / White Spots / Dots Appearing on Rubber Side of Components & Cable?
I have encountered similar occurrences in the past, and it turned out to be a breakdown of the plasticizer in the material.

If the residue was on other components, I would suspect it was fungus forming.  But since it appears to be only on the heat shrink tubing, I believe it's a chemical instability in that one material.  This usually takes a few years for the residue to become visible.