Given the rather obvious clues this show has dropped in the past, however, I can totally see why some people were fooled into thinking the show would put such a big clue in plain sight.
With the Kitty, perhaps the costume was inspired by another celebrity, such as Kate Bosworth.
That was a popular choice given her heterochromia matches that of The Masked Singer’s Kitty, but now it seems that may have been too obvious of a misdirect.
Perhaps going forward, we should all be a bit more leery about judging these costumes!