We get a lot of goldfinches in the garden but I’ve never seen one looking like this. I thought it might be a juvenile but after googling now I’m worried it’s an adult with some disease. Here’s the inat link: http://www.inaturalist.org/observations/93144243
You should look on how it moves or doesn’t, is it closing eyes, etc. puffing up can be a sign of illness, but it can also be just a cold day for this bird.