Was 14k lines carefully reviewed? Seems unlikely.
I carefully review far more than 14k LoC a week… I’m sure many here do. Certainly the language you write in will greatly bloat those numbers though, and Node in particular can be fairly boilerplate heavy.
Considering the many hundreds of technical comments over at the PR (https://github.com/nodejs/node/pull/61478), the 8 reviewers thanked by name in the article, and the stellar reputations of those involved, seems likely.