I know what an environment variable is, my question is why name them `UV_` instead of `FYN_`? I thought that would've been obvious for exactly the same reason you mention, it should be named for the application they belong to.

Ah, I completely missed the point of your question :).

Yes, I think that's a good point. Possibly they were made before the project name was changed and no further thought was given to them after.