Why is this happening? I've had this phone for like 5 months and the cable gets more and more green every time I use it. It also gets hot enough to try an egg on while fast charging.
Probably this or moss if something pissed on it. Though it is possible that algae also started growing on it if it was left in a puddle of piss for long enough.
Whatever the cause, you need to wipe it down with a disinfecting wipe OP.