I vape a lot of menthol juices and haven't had that kind of discolorization... it may be from sweetners in the apricot. I had huge discolorization from 12 monkeys juice when I tried it (worse than what youre seeing) and it has a lot of sweetners in it and is also known as a coil killer
I'd actually be interested that recipe... is it similar to the Champlain juice from Adirondack?
Is just a very normal recipe, nothing special but I like it:
Apricot Atmos Lab 6%
Sweetener FW 2%
Menthol 2 drops per 10ml