New or niche languages always have their projects advertising their implementation language as a point of interest, basically as marketing for that language. You'll rarely see "In C" or "In Python" because those are just known-popular choices. (Not never of course, but rarely.) By contrast, I bet we're going to see a lot of "In Nim" in the next year.

Go's actually on the tail end of that right now; I've seen a number of things posted to HN that are just implemented in Go without saying so. Of course if you don't click through and look, you won't notice. :) But at this point, if I click through to a GitHub of some project and it's in Go, it's only mild surprise at best; it is most of the way to being just one of the default choices.

There's an even earlier version of this phase, which is when all the projects include the language in the name of the project, i.e., "gosql", "gobrowser", "punwithgo", etc. Go's been out of that one for long enough that I think it's kinda off when a new library has "go" in it unless there's a really good reason (for instance, development tools that really are about Go specifically and not just implemented in Go).