I’m a colubrid guy but deal with the Arizona mountain kings, various garters, but no rat snakes. I do know there is a leucistic Texas rat snake but they remain leucistic throughout life. They are sought out in the hobby and are pretty much available. I would not be surprised if this is some sort of hybrid that has been sensationalised. This is just my personal take and I may stand corrected. Your initial photo I believe to be a Leucistic Texas rat snake. The colored individuals I think may be hybrids.