I totally agree with Noodles, that is absolutely NOT from a molt, but rather from either a "Brood-Patch", as Noodles suggested above, or just from general plucking...But again, it's in the right location for it to be related to sex-hormones...However, we can't see the rest of her feathering on her wings, back, around her neck, etc., so if you see any ragged-ends on any of her feathers elsewhere, or any other areas of the same type of plucked-appearance that is only on one side and not both, then that's a good indication that it's plucking and not hormones.
As Noodles stated above, it is breeding-season (my Senegal just won't stop insisting that I eat his vomit, and my female Cockatiel keeps putting her butt on my neck and chirping...gotta love it), and there are a lot of different things that you could be doing or giving to her/allowing her to have or do that is causing her behavior....I don't know if you normally handle her like that, but you shouldn't touch her anywhere near her legs, lower belly, tail, and yeah, near her vent, right where your fingers seem to be in the photo, lol...You should only pet them on the head, neck, face, and under their chin. That's really about it, especially during Spring and Fall, the two normal breeding-seasons...
****Extremely important is if there is ANYTHING in her cage that creates a small, dark place that she can get inside of or underneath, such as a Nest of any kind, a Bed of any kind, Tents, "Cuddle/Snuggle/Happy Huts" (which kill thousands of pet birds every year anyway, so they need to be thrown-away for numerous reasons), Hammocks, or any types of Boxes in-general...Also, nothing in the bottom of her cage that could be considered or used as "Nesting Material", such as wood chips, any type of Animal-Bedding like Crushed Walnut-Shells, Corn-Cob Bedding, Shredded Paper, or any Towels, Blankets, Pillows, etc...You should only use SHEETS of Newspaper, Butcher-Paper, or proper Bird-Cage Liners in the bottom of her cage, and they should always be UNDERNEATH THE GRATE in the bottom of her cage so she can't get to them and use them as nesting-material or get underneath them...Also, never let her get underneath of the furniture, behind pillows on the couch or bed, underneath covers/blankets, etc. when she is outside of her cage, as this does the same thing as having a Happy-Hut, a Bed, a Tent, etc. inside of her cage...
And also, no feeding her any Warm, Mushy Foods, such as Oatmeal, Grits, Mashed Potatoes, and definitely no Baby-Bird Handfeeding-Formula EVER, unless she becomes quite ill and the Avian Vet prescribes it to her...
All of these things trigger their sex-hormones to go nuts, which they already are right now during this time of the year, and in a female bird this can cause them to start plucking in that particular area in-order to make a "Brood-Patch", which female birds do naturally whenever they are laying eggs/raising chicks...And for male birds it also still can cause Feather-Destructive Behavior, which it can in females as well...So it's not necessarily true that what your bird did was make a Brood-Patch, but that's the general area one would be in...If you see any other signs of plucking/barbering of her feathers on her wings, her back, the back of her neck, her shoulder-caps, etc., like ragged-ends on all of the feathers in an area, then that's plucking, which could be due to hormones, but is typically due to something such as boredom, stress, frustration, or a medical/health issue such as a Systemic or External Yeast/Fungal Infection, Bacterial Infections, and then this brings me to the not so good part of this discussion...
I don't know when she has had her last Wellness-Exam with a Certified Avian Vet or Avian Specialist Vet (No "Exotics" Vets for this unless they are also a CAV), but they can also pluck themselves the way your bird has due to them producing Follicles and/or Infertile Eggs (meaning she is going to lay an infertile egg soon, and you need to watch for any signs of her "straining" to push the egg out, like she has to poop but can't, because if you see that then she may be egg-bound, which requires immediate medical intervention right on the spot), and they also pluck their bellies in that area when they are experiencing pain, nausea, and other health issues and illnesses...SOOOOO, that leaves me with the question about her last Wellness-Exam that included full Fecal-Testing and full, routine Blood-Work, which she should be having at least once every year, and which you'll need to keep a close eye on her and if you notice any other signs/symptoms of illness or pain, she stops eating/drinking, any vomiting, loose/watery droppings, she starts sleeping more than normal or stops moving around much, stops playing like she normally does, etc., then you need to get her in to an Avian Vet ASAP for Fecal-Testing and Blood-Work...
She may lay an egg, she may not, either way see if you are doing anything or giving her anything that could be causing hormonal-behavior and remove it/stop it (especially anything inside of her cage like a "Hut" or any other type of "box" or "tent"), and try to make sure that she has lots and lots of different types of toys inside of her cage at any given time, ones for chewing, ones for shredding, ones for foraging, etc., and also make sure that she is getting ample out-of-cage-time every day, at least 4-5 hours a day, every day...And also make sure that she's getting at least 10-12 hours of solid sleep every night as well, as that's another common cause of hormonal-behavior...
