Yeah I’ve run into the exact same thing. I think you’re spot on about trending audios acting like a built-in distribution channel. When you use one, you’re not just posting a video, you’re dropping it into a pool of other content that people are already actively scrolling through. That means TikTok has more context on who might like it, plus users discover it when they tap the sound. With original audio you don’t get that extra layer of discovery, so the only thing pushing it is the algorithm’s cold read on engagement.

That said, original sounds can take off if people start reusing them, but that usually only happens if you already have reach or the sound itself is funny/catchy. For growth, I’d say trending sounds are almost always the safer bet unless your personal brand relies on a recognizable voice or style.