What?

It is what is

Isn’t “designed” to short circuit cognitive dissonance…

I mean, it kind of could be put that way, but only because OP doesn’t seem to know they said the opposite of what they meant to from context.

It is what it is

Means

This is fucked, but I can’t help

It’s not to trick someone into ending a discussion, its commiserating over a shitty situation.

To let the other person know you’re not talking about what’s right and what’s wrong. Just stating how something is.