Google announced the May 2022 core update on May 25, 2022, around 11:30 am ET, with the blog post "May 2022 core update releasing for Google Search". It was the first core update in more than six months, following the November 2021 core update, and Google estimated it would take about 1-2 weeks to fully roll out. Search Central announced completion on Twitter on June 9, 2022, 15 days after launch.
Unlike some rollouts that build slowly, this one moved early and hard: data providers described it as a big update that rolled out quickly for many of the queries they tracked, notably more significant than the November 2021 core update, with the heaviest volatility of the rollout recorded around June 5.
Google's framing at launch was the standard core-update message: these are changes "to improve Search overall and keep pace with the changing nature of the web", nothing in them targets specific sites, and "a negative rankings impact may not signal anything is wrong with your pages". If your site moved in the May 25 to June 9 window, audit the affected pages against the self-assessment questions in Google's core updates documentation; some recovery can show between updates, but the biggest changes tend to register at subsequent core updates. Our recovery guide covers the sequence.