I don't know if there's a named law, but the word for not knowing and believing that something remembered is a novel idea is "cryptomnesia".
Knowing that you know something by teaching is Feynman's method of understanding. Basically, on scanning, I don't particularly disagree with the content of the post. However, treating these things (many of which regularly show up here on HN) as being due to "14 years at Google" is a little misplaced.
But, hey, it's 2026, CES is starting, and the hyperbole will just keep rocketing up and out.
This is Goodhart's law - "When a measure becomes a target, it ceases to be a good measure" [1].
[1] https://en.wikipedia.org/wiki/Goodhart%27s_law