Yes, but it's not like this only happens with small/new languages. Even today, Go-lang binaries will often get detected by various Windows anti-malware software. They even have a section in their FAQ about it [0].
Also, in Hare's specific case, it doesn't _really_ matter as they will never support Windows or MacOS [1], and there isn't a significant presence of anti-malware software on linux distros.
Not supporting Mac is a big shot in the foot from Hare. Is this a case of ideology getting in the way of pragmatism, or do they have technical reasons? Singling out proprietary platforms sounds ideological.
"As other commenters alluded to, it's an ideological and practical decision. We simply prefer free software operating systems. We do not care to legitimize nonfree platforms, and we prefer to be able to read (and patch) the code to understand the tools we depend on. If that's a deal-breaker for you, no worries - Hare does not have to appeal to everyone to achieve its goals."
Hard to say, since we have no idea how the antivirus vendors are identifying nim. Maybe there's something about the fact that nim compiles to C which is then usually compiled by mingw? (You can use compilers other than mingw, but it's the default).
Mingw might have a higher weight for "this is malware". Then you combine that with nim generating code that's common across most nim binaries (the GC, boilerplate symbols, etc).
Then there's perhaps not enough positive signals to offset that, since there's not yet a wildly popular windows app written in nim.
Also, in Hare's specific case, it doesn't _really_ matter as they will never support Windows or MacOS [1], and there isn't a significant presence of anti-malware software on linux distros.
[0]: https://go.dev/doc/faq#virus
[1]: https://harelang.org/platforms/