I doubt it, due to how the leak is purportedly from 2017/2018 code, and according to the tweet from SteamDB is the version that is included to Source engine licensees.
There are YouTube channels like VNN that rely on Valve leaks, but most of it seems like running `strings` on their update files. He does claim to have some inside sources, but they mostly seem to provide social commentary on Valve internal politics.
The original hl2 code leak was a fan from Germany that hacked into Valve's network and stole a version. https://arstechnica.com/gaming/2016/06/what-drove-one-half-l...
There are YouTube channels like VNN that rely on Valve leaks, but most of it seems like running `strings` on their update files. He does claim to have some inside sources, but they mostly seem to provide social commentary on Valve internal politics.