I have spoke about this condition with @Action Jackson and he has seen it on one of his animals, again seemed to be benign but we were unable to determine a cause. I would be interested to see if you find any more information about this.
I have seen this before in my nosy be male. It seems to be benign as the color change happened around the year two mark and he is almost 5 now. Does the discoloration seem the affect only one side of the tail?
Chameleon academy https://chameleonacademy.com/ is the best source of info and will give you the best start. The best advice is set up everything well in advance of getting your chameleon and do not cut any corners. It will be expensive up front but will pay off in the long run. Try to...