Brown, gray feathers? Does this look like molting? He is losing his green. Gray feathers on the bottom of cage. Yesterday I also found Feathers with green and gray.
That's a moult. The grey is probably down, the picture looks ok. Is his beak colour bright? Are his feet pale or dark? (They should be pale, otherwise there's a circulation problem)
Poe had a grey-ish look to his feathers when he was moulting, but then he has some immune problems and is low in vitD.
Not sure what to say. Has he had blood tests done?