>>111433225It's not.
I don't know what circles you're running in where it may be used that way, but by and large, it's not. Boomer humor is humor for people in their middle age or above. "OK Boomer" is mostly aimed not at the new parents of the millennial generation, but the older parents of teenagers, the ones sending their kids off to college, or retiring.
Please, stop changing the meaning of words to whatever is convenient.