Hello, I agree with you: this kind of ring makes this a quite sure escape.
Whitish ground colour meens its some kind of colour mutation, but species is more difficult, at least fo me:
first thinking is (of course) a Canary , but streaking seems wrong (unusual?) for this: narrow, fine and distinct on back and flanks.
I am not an expert in domestic birds and their variation, so I hope for others to jump in and identify this bird.