Unfortunately Linden, this is not normal. There is one new feather in that picture and it looks normal and unaffected. The rest are not new and not normal. He is a downy chewer for some reason.For some reason he's lost a bunch of feathers from that area. The 'stubs' would appear to be the new feathers growing in. When he bites them and the white stuff comes off he's just breaking the sheath off. Looks totally normal other than the feather loss.
Yeah, sometimes I catch him chewing that area and when he is preening. Due to the winter, he hasn’t bathed but the weather is warmer now so I’ll definitely get it going.A bath will never hurt. You should make sure they bathe regularly.
There are many reasons for over preening. It be diet, stress, illness. Have you noticed that she is chewing that area lately?