Are unlisted threads still accessible via Google searches?

[InquilineKea (Alex K. Chen)]

Eg: this topic is unlisted on my forum, is it visible to Google

https://www.rapamycin.news/t/does-anyone-use-screen-capturing-software-so-you-can-search-reference-across-your-entire-browser-history/5625

[sam (Sam Saffron)]

We include a special HTTP header telling google not to index it. (X-Robots-Tag: noindex)