People are writing production level databases, distributed systems in Go... ofcourse it's a systems language unless your definition of a systems language is something super narrow.

There’s some places you can’t use a language with a large runtime like Go. For example, operating system kernels, real time embedded systems, game engines, anywhere you want to be extremely careful about memory allocations. You can write go for most of these use cases as toys and demonstrations, but this is where languages like C dominate and Rust/Zig are making inroads because of the ability to execute on bare metal with no runtime.

When I think of systems languages, I think of languages that are suitable for all of those use cases, but also for writing operating systems and code for embedded microcontrollers. Writing a kernel in a language with garbage collection is possible, but would it really be optimal compared to writing a kernel in other languages without it?