It's hard if it's more different to what one knows, of course. Kotlin was easy for me, Rust took a while, probably based on languages like Python, Dart and especially Java that I knew.
I think that maybe in the beginning the high level abstractions are hard. And having a strict and explicit language makes it hard to get started. Safety features like types and ownership are an initial obstacle as well.
But when trying to master the language and write correct programs quickly, it's kind of the reverse: you want the language to enforce discipline and to be unforgiving of possible mistakes at compile time, because otherwise you have to keep many details in mind, or you're gonna be debugging a lot.
Overall, I don't really think it's frustrating, it's a lot of fun. The only thing that's frustrating is setting things up, like IDE, package manager, build tools...