Blocked due to access forbidden (403): search/{search_term_string}/

Hello!

Google crawls anything that remotely looks like a URL. In this case, we use Schema.org syntax to identify Sitelinks search box, and they crawled the syntax URL: https://developers.google.com/search/docs/appearance/structured-data/sitelinks-searchbox.

Their example script also uses search_term_string:

<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "WebSite",
  "url": "https://www.example.com/",
  "potentialAction": {
    "@type": "SearchAction",
    "target": {
      "@type": "EntryPoint",
      "urlTemplate": "https://query.example.com/search?q={search_term_string}"
    },
    "query-input": "required name=search_term_string"
  }
}
</script>

You probably have a firewall enabled that blocks brackets ({}) in the URL. You can safely ignore the issue and keep the firewall running as-is — Google’s crawler doesn’t recognize Schema.org structured data; it only forwards whatever it found to their actual structured data parser (which doesn’t test the URLs given).

Thank you for the detailed explanation.
I have a the 7G firewall rules in .htaccess, which may well be blocking those curly brackets. However, as there is no negative impact on SEO I’ll go ahead and ignore this warning.
Cheers!