Have you wondered why this is the case? How do you think they increased impressions so much at their scale? How they did this despite losing 20M users?

To put it clearly, AI at every part of the pipeline: writing software, product features/experiments, A/B testing them, and pushing them out to users. Even before you get to something like LLM driven recommendations, you can virtually entirely automate the process of finding more "engagement alpha" with AI.