“Their own” is a bit misleading. It’s largely a subset of the people who implemented libjxl in the first place, but this time in Rust.
The top three contributors to the reference implementation are also Google employees. https://github.com/libjxl/libjxl/graphs/contributors?all=1
I'm sure those implementers got their fair share of the Google profit or at least a nominal donation for doing most of the work of building out a feature enhancement
right?