Are the white strands pin feathers? Sometimes a bird can look patchy during a molt. But I've increases offer foods with more protein during molt and have never had that problem since. Like scrambled eggs, boiled chicken, walnut, other nuts, giving a few extra seeds.
How old is your bird? What do you feed? Is your bird picking up on your stress? How much out if the cage time? Cage placement of? Tons if easy to destroy stuff? Mine like yucca chips, paper, cardboard, those shredders rolls, likes untie knots. Offer more baths. Feed hot chili peppers, good source of vitamin A and well liked by parrots, dried ones still have vitamin A
That is common area to start plucking. But also can indicate an isuue with crop, like impaction from threads and fluff, or yeast overgrowth.
You can offer a little fresh just opened live culture yogurt, with no artificial sweeteners. Mine get some when ever I eat yogurt. Will help if there is an imbalance. Helped my GCC get over a yeast infection. Learned here from other member! One if the best tips!
Welcome to the forum! Beauty GCC! Love the color!!
https://lafeber.com/pet-birds/stress-reduction-for-parrot-companions/