[ploxiln]

That's exactly it. After "shipping the work to production" (making it faster for everybody), the overall average and p95 got worse. Each sub-population experienced improvement: countries with fast internet got faster youtube, countries with slow internet got faster youtube. But the overall average and p95 got worse: overall average was slower youtube. Because now more users from the second sub-population bring the overall average speed down (or latency up). That's Simpson's paradox.

[kgwgk]

Ah, you may be right. It's not clear in the story that "Average and p95 latency actually increased after shipping the work to production." means average of Indonesia and ex-Indonesia and not just Indonesian average.