In my opinion, one of the most underrated things by people programming in C# is the fact that they also have F# at their fingertips. They ignore it because they haven't dedicated enough time to appreciate how powerful and fantastic it is.
It's less that and more things that work in C# will not work in F#, and the community doesn't have enough support for it. If you use .NET for its tooling, you lose some of that with F# and wonder if you should just use a different ML language.
Want Entity Framework on F#? Code generation is broken past .NET 6. Huge pain in the ass to fix. Using Dapper is fine, but EF is nice for more than avoiding SQL.
Want Swagger support on Giraffe? They're rethinking the whole structure just to imagine how that would work.
It's very much a separate world unless you use a lot of C# directly, and that kinda defeats the point.