Even production/pet quality BRs should always have yellow legs, always. THere are varying degrees of color intensity, but the color must be yellow.
One thing that bothers me is that an entire bunch of birds got the white legs. If one or two in a huge hatch came out with white legs, you might say they were throwbacks to something bred in at one time or a fluke, but when all of them show up with the wrong leg color, then I'd consider that a crossbreed. Even if someone adds in blood from another breed for some reason, they still have to cull heavily to get the birds back to their correct standard. If they are very often popping up with wrong traits, then they did not cull heavily, IMO, and you can't really consider that line of birds pure. I hope I said all that right and it makes sense, LOL. I dont consider myself a breeder and certainly not a genetics expert, by any means.