The article is not correct on that point. At Google we would create release branches to fix the monorepo at a predictable point for testing, and only cherry-pick what we need during the release process.
I'm sure others do similarly, because there is no way you would allow arbitrary changes to creep in the middle of a multi-service rollout.
The multi-service staggered rollout is the reason the article is correct unless you are tolerating contract mismatches somehow other than in the code. not at google so won't be guessing.
...and the article points out correctly that it's a lie anyway, but at least you can find all the consumers easily.