Rare Yellow-rumped Audubon’s Warbler?

This strange yellow-rumped warbler came to eat peanut butter this morning. It was silver, it had the normal yellow-rumped warbler markings, but no yellow rump! Is this an Audubon’s subspecies, a Mytrle x Audubon’s hybrid, or just a normal myrtle yellow rump? Any ideas?

Yellow-rump on lawn chair

Yellow-rumped Warblers

I was sitting outside today watching the birds. There were probably about 50 yellow rumps foraging and eating mosquito hawks in the grass. They come every day and eat peanut butter