That phrase is often used to move goalposts when someone is using an anecdote to justify actions they've taken, or policy they're advocating. This can include leveling accusations at other people.
It is a linguistic tactic that attempts to bypass debate through appeal to emotion. "You can't tell me I don't feel this way!" Correct, you feel that way, but your feelings don't magically turn assertions into fact. The objection of "invalidating lived experience" is the notion that one's feeling are facts when they are not. They are subjective impressions unsuitable as the sole grounds for action.
It is a linguistic tactic that attempts to bypass debate through appeal to emotion. "You can't tell me I don't feel this way!" Correct, you feel that way, but your feelings don't magically turn assertions into fact. The objection of "invalidating lived experience" is the notion that one's feeling are facts when they are not. They are subjective impressions unsuitable as the sole grounds for action.