Strange given/when deparsing

[KSURi]

Hello, monks!

There is a simple script:

use Modern::Perl;

my $x = 2.3;
given($x) {
    when(int) { say 'match' } # int($_) ~~ $x
    default { say 'no match' }
}

It prints 'no match' as expected.

There is also another script with a little difference:

use Modern::Perl;

my $x = 2.3;
given($x) {
    when($_) { say 'match' } # $_ ~~ $x
    default { say 'no match' }
}

Prints 'match' as expected.

The strangeness is that B::Deparse produces the same output for both scripts:

use Modern::Perl;
use warnings;
use strict 'refs';
BEGIN {
    $^H{'feature_say'} = q(1);
    $^H{'feature_state'} = q(1);
    $^H{'feature_switch'} = q(1);
}
my $x = 2.3;
given ($x) {
    when ($_) {
        say 'match';
    }
    default {
        say 'no match';
    }
}

Why is this so? Is this a bug of B::Deparse?