I checked also the XTOL stored in the lab, and it had the same let's-call-it-fungus. As I looked at the other bottles I have, it seems to me that the fungus is everywhere: in wetting agent, in print dev, in D-76… The only chemical that lacks it, is fixer. I sure am going to use distilled water instead of tap water the next time I mix anything.

Anyhow, for me the fungus does not seem to alter the developing results.