Valid feelings and validation are unrelated.

The good kind of "valid" is about whether (a) your process of measuring reality might be broken to your detriment. And by extension (b) whether your communications channel with the person you are talking to is working.

Chris Voss's mirroring is basically TCP ACKs.

Then there are the people who say that they lack validation and are just narcissists looking for yes-men. Big difference on how much of your time is being wasted.