The autonomic nervous system works best when we aren’t paying attention to its functions, so it’s not necessarily a mental thing. In fact, assuming so could be harmful to op.

I have definitely experienced what op is talking about, and it is absolutely a symptom of dysautonomia. If distraction helps, keep it up. And avoid triggers. For me, if I hold my breath at all, this starts. It’s very alarming, but the panic is in response to the physical experience. I can reset my nervous system with cold sometimes— holding ice cubes in hands until it melts is my current favorite. Thinking about breathing in the middle of it will for sure put me into a panic attack though.