The author linked to wrk2 but I think he ended up using a k6 executor that exhibits the problem wrk2 was designed to solve.
Yep, k6 suffers from coordinated omission [1] with its default settings.
A tool that can send a request at a constant rate i.e. wrk2 or Vegeta [2] is a much better fit for this type of a performance test.
1. https://www.scylladb.com/2021/04/22/on-coordinated-omission/