Correction: it spawns several pseudo-processes on windows which are all emulated inside the main process.

That's also why taskkill can't work, the $child_id you get from fork is meaningless for the OS.

https://perldoc.perl.org/perlfork#SYNOPSIS

On some platforms such as Windows where the fork() system call is not available, Perl can be built to emulate fork() at the interpreter level. While the emulation is designed to be as compatible as possible with the real fork() at the level of the Perl program, there are certain important differences that stem from the fact that all the pseudo child "processes" created this way live in the same real process as far as the operating system is concerned.