Why discord is switching from go to rust (2020)

go's experimental memory arenas feature could lessen the pain of gc in a lot of cases

Just use a language with better GC’s or one where you have the ability to manage memory yourself in hot paths

It's rather about Go's inadequacy and shortcomings as a language. They could write C# or Java Go-style and get much, much higher throughput and efficiency. C# also lets you write lower-level and/or Rust style code to push the language which is not an option in Go.