From de- +‎ preference.

depreference (third-person singular simple present depreferences, present participle depreferencing, simple past and past participle depreferenced)

1. To cause something to stop being preferred by a search engine algorithm.
   • 2008 October 23, Josh Karlin, Stephanie Forrest, Jennifer Rexford, “Autonomous security for autonomous systems”, in Computer Networks, volume 52, number 15, Amsterdam: Elsevier, →DOI, →ISSN, →OCLC, page 2916:

     We predict from this experiment that depreferencing short-term routes would have little negative impact in practice, as most affected routes are misconfigured, non-optimal routes discovered during convergence, or attacks.

   • 2012 September 18, Benjamin Edwards, Tyler Moore, George Stelle, Steven Hofmeyr, Stephanie Forrest, “Beyond the blacklist: modeling malware spread and the effect of interventions”, in NSPW '12: Proceedings of the 2012 New Security Paradigms Workshop, New York, N.Y.: Association for Computing Machinery, →DOI, →ISBN, page 61:

     In a related intervention, Google has successfully pushed ad-filled sites down the results by changes to its search-ranking algorithm, suggesting that a similar effort to depreference malware-infected sites is technically feasible.

   • 2015 August, Huw Fryer, Sophie Stalla-Bourdillon, Tim Chown, “Malicious web pages: What if hosting providers could actually do something…”, in Computer Law & Security Review, volume 31, number 4, Amsterdam: Elsevier, →DOI, →ISSN, →OCLC, page 502:

     In reality though, the circumstances for the scenario of blocking or 'depreferencing' a malicious Web page are different.

   • 2023 January 21, Cory Doctorow, “Tiktok's^[sic] enshittification”, in Pluralistic‎^[1], archived from the original on 19 April 2023:

     Tiktok^[sic] won't just starve performers of the "free" attention by depreferencing them in the algorithm, it will actively punish them by failing to deliver their videos to the users who subscribed to them.