Maybe some other numbers are more relevant? This blog post from April 2022 mentions 1000+ services:

  https://medium.com/airbnb-engineering/continuous-delivery-at-airbnb-6ac042bc7876

And this video from May 2017 mentions 1B daily events (for whatever they define as an event):

  https://youtu.be/70luTZU-D3E?t=102

It wouldn't surprise me if they're storing calls between microservices as "events" and they're likely logging a lot of both user data and internal services data, but that's purely a guess.