C# is a decently-designed language, but its first principles are being microsoft-y and java-y, which are perhaps two of my least favorite principles. that aside, i've worked on C# backends deployed to lots of linux boxes and it's not really second-rate these days.

Microsoft's implementation has been cross platform for almost a decade now. You're way too late to the Mono FUD party.

Almost a decade? Amazing. Considering go has been cross platform since its inception almost twice as long as that, rust too, it’s no wonder developer mindshare is elsewhere.