Robots.txt vs. noindex meta tag

[riddla]

(As this might not be an issue of the module and maybe a misunderstanding from my side, I'll post my question here.)

I recently discovered via the Google Search Console that parts of two of our staging systems are indexed by Google. Reading further into the topic (https://developers.google.com/search/docs/crawling-indexing/block-indexing?hl=en), my current understanding is, that using both techniques (blocking pages via the robots.txt and the noindex meta tag) together won't stop Google from indexing it (or won't remove URLs from the index):

If the page is blocked by a robots.txt file or the crawler can't access the page, the crawler will never see the noindex rule, and the page can still appear in search results, for example if other pages link to it.

Am I misreading the Google docs? Or are our staging systems configuring the nuxt-simple-robots respectively nuxt-site-config wrong?

We are deploying our staging sites with indexable: false with the siteConfig.

The output of http://localhost:3000/__robots__/debug.json is as follows (which should mimic the configuration that is used when our staging sites are prerendered):

{
  "robotsTxt": "# START nuxt-simple-robots (indexing disabled)\nUser-agent: *\nDisallow: /\n\n# DEVELOPMENT HINTS: Indexing is blocked by site config set by nuxt-site-config:config.\n\n# END nuxt-simple-robots",
  "indexable": false,
  "hints": [
    "Indexing is blocked by site config set by nuxt-site-config:config."
  ],
  "runtimeConfig": {
    "version": "4.0.0-rc.10",
    "usingNuxtContent": true,
    "debug": true,
    "credits": true,
    "groups": [
      {
        "userAgent": [
          "*"
        ],
        "disallow": [
          ""
        ],
        "allow": []
      }
    ],
    "sitemap": [
      "/sitemap.xml"
    ],
    "robotsEnabledValue": "index, follow, max-image-preview:large, max-snippet:-1, max-video-preview:-1",
    "robotsDisabledValue": "noindex, nofollow"
  },
  "siteConfig": {
    "env": "development",
    "indexable": false
  }
}

[riddla]

@harlan-zw, could you have a look?

[riddla]

Ping @harlan-zw :)