Wing spreading is often a side of dominance and more often seen in females than males and is the birds way of claiming their space, sometimes ot is also a form of exercise, I also heard from a breeder that some birds do it to show how attractive they feel(which makes sense because Frost has done it to my sister's budgie who she has a crush on and was laying a huge amount of eggs when they lived next to each other.) So maybe your bird is feeling good about him/herself .
This picture is dark but here is an example of Frost doing "batwings" she was in a very good mood that day, so I dont think it was a dominance thing. She doesnt flap while doing this just hangs. Is thisbwhat your bird is doing?
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