Maintainers of all open source standard libraries are effectively "random third parties". With heavily used ecosystem dependencies (such as Tokio, but also swaths of small libraries, such as `futures` or `regex`), the number of people who have looked at the code and battle-tested it is also huge.

On crates.io, a good heuristic is to look at two numbers: the number of dependents and the number of downloads. If both are high, it's _probably_ fine. Otherwise, I'll manually audit the code.

That's not a complete solution, especially not if you're worried about this from a security perspective, but it's a good approximation if you're worried about the general quality of your dependencies.