The phrase that's true, no agenda circulates online as a standalone reaction clip rather than as part of a longer known recording, and its exact origin is not documented. Its appeal comes from the wording itself, which sounds like a denial and an agreement at the same time, making it useful for ironic replies. Short voice lines like this spread through soundboards and chat sharing because they are easy to drop into any conversation without context. It remains popular for low-key humour where a calm confirmation feels funnier than a loud reaction.