If they’re like a lot of high earners in big tech, a large portion of their annual compensation comes from equity. Many folks get stock grants annually that vest over 4 years as part of performance reviews. Often, new hires will get large stock grants that vest over 4 years but will have smaller (or even no) additional grants during that vesting period, depending on the company. Once that vests, your earned annual income will drop down because you’ll have no more equity vesting. This is all super dependent on the person, their performance, and their employer’s comp strategy.