Four signals decide whether a page can be indexed, and they can contradict each other without anything looking broken. A canonical pointing elsewhere hands the ranking to another address. A noindex behind a robots.txt block is never read, so it never takes effect. This fetches the page, fetches its robots.txt, and lays the four side by side.
The page and its robots.txt are fetched once from this server, with a plain GET and no cookies. Requests to private networks, to loopback and to link-local addresses are refused, including through redirects. The query is protected by reCAPTCHA v3; the calling IP address and the target are stored for one hour to limit the rate.