The colorful mage is a peacock?

It's not a peacock. You're delusional. A couple of reasons:

1. The last Vastayans were Rakan and Xayah, both bird people. It'd get way repetitive if a new Vastaya was also a bird person, especially a bombastic, colorful bird like a peacock. It'd overlap Rakan too much.
2. Notable in just about every mention of the colorful mage in the Roadmap months ago was the words "HIDDEN" and "HIDING." Peacocks don't hide. They're in your face, gorgeous birds.

There is ONE animal that fits this bill. There is a colorful - more specifically, a color changing - animal that uses this talent to hide. A chameleon.

is a peacock-person.

Whatever it is i hope it's just none human, preferably a totally new species to leagues' lore.