Copyright covers the prompt, it's not even clear why it should be relevant for the output of the AI software based on that prompt.
https://www.sidley.com/en/insights/newsupdates/2025/02/us-co...
"Prompts Are Generally Insufficient to Make AI Output Copyrightable"
If you don't trust this summary, read the US Copyright Office report for yourself. The gist of the position is that prompts are not specific enough and do not lead to deterministic output.
On a side note, I find it weird that even on HN people automatically assume you're only expressing a personal opinion, yet in all fairness I should have included some references from the start.