On windows, there are APIs for setting color that could be ignored if STDOUT isn't a terminal.

On posix platforms, there's an API to check if a given file handle is a tty or not. https://github.com/corasaurus-hex/isatty/blob/main/isatty.c is an example of using the API, in a Janet context.

I assume that .NET's support for Linux/macOS is using that API decide if it should strip color codes or not.