No, there's no "Tail Rot" there at all, her tail looks completely normal. Most dragons have a darker end to the second half of their tail, it's just normal coloring and no issues at all.
In order for them to suffer from "Tail Rot", which is a general infection of the tail that spreads upwards towards their body, killing all of the tail tissue along it's way, they have to either have an open wound of some kind, like from a bug bite or a bite from a sibling, or from getting their tail caught in the tank door, etc., or they have to have a band of retained shed that didn't come off, and that is cutting the circulation off to the tail below it. In either case, the tail tissue below the infection or retained shed turns pitch-black, shrivels up, and eventually falls off, and this infection and blackness/necrosis of the tail tissue continues to spread up the tail towards the body, unless they get medical intervention, usually by amputating above the infection line.
Trust me, if she ever develops "Tail Rot" you'll know it, it's a nasty infection and their tails shrivel up, turn hard as a rock and black as coal, and fall off. Your dragon's tail is perfectly healthy and normal.
