Please explain how and why value of @_ is keeps changing in same subroutine "formatlist" in below code

[root@mail ~]# perl test.pl -w
-w out  return
Command Line in return
Command Line: -w

[root@mail ~]# cat test.pl
sub formatlist
{
    my @list = @_;
    print @_, ' out  return', "\n";

    return sub
           {
               print @_, ' in return', "\n";
               my $title = shift;
               print "$title: ", join(' ',@list),"\n";
           }
}
$arguments = formatlist(@ARGV);
&$arguments('Command Line');

[root@mail ~]#

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In reply to @_ & @ARGV by dushyant

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