A URL still appears in Google after you blocked it in robots.txt. The file controls whether Google may fetch an address. A known URL can remain eligible to appear without Google seeing its updated content.
A readable noindex instruction serves a different purpose when a public HTML page should leave the index. It does not provide access control for confidential material.
Different controls, different outcomes
Consider this fictional configuration:
robots.txt:
User-agent: *
Disallow: /preview/
<meta name="robots" content="noindex">
If the meta element belongs to /preview/offer/, the crawling block may prevent Google from fetching it. Protect a confidential draft with authentication. There is no reason to expose private content merely to let a crawler read an instruction.
Inspect the affected address
Record the HTTP status, robots meta element and any X-Robots-Tag response header. Then inspect robots.txt on that same host. A www hostname and its non-www counterpart can return different configurations. Decide whether you are excluding public content from search or restricting access to private material.
For a public page intentionally excluded from search, Google needs access to the indexing instruction. After changing the configuration, test the live URL in Search Console. Also check when Google last crawled the page.
The indexability checker examines visible signals. Check Google’s actual index status separately in Search Console.