My brother is an Xoogler, who told me a few years ago there was a de facto 3-year "up or out" policy. That is, if you go 3 years and haven't been promoted, you should probably expect to need to find work at another company.
Itβs L4 as of like a year ago; also going up to L5 no longer has promo committee per-se, but instead is a PA meeting between leads who hash it out, and the manager is much more involved.
with that kind of policy, it's no wonder they can't retain talent. Since most people can't be promoted, then they have no choice but to leave or get laid off.