Post-mortem: approximately 24-48 hours ago, Patreon inadvertently added to their entire root-level domain. This had the effect of deindexing all of http://patreon.com (including all creator pages) from every online search engine.
It took them four hours from my reporting to fix it. Most pages (including their homepage) were already deindexed, so it was probably noindexed for at least 24+ hours. It will likely take 7-28 days for the pages to return to search results for everyone.
via Mastodon