"Sometimes a promotion comes too late, and the employee has already started looking, Richardson says. Other times, a LinkedIn update with the job news causes outside recruiters to take notice."

https://www.wsj.com/articles/getting-promoted-often-leads-to-jumping-ship-new-data-reveal-cc95f1fc (https://archive.ph/6exxN)

Or more likely, once you had a new job title, you can make more money somewhere else and start working on your next job title there.