you didn't use my for your variables.

update

use v5.12.0;
use warnings;
use PadWalker qw/peek_my peek_our/;

my  $a1 = {};
our $a2 = {};

for my $space ( peek_my(0),peek_our(0) ){
    for my $item (keys %{$space}) {
        say $item if (ref ${$space->{$item}} eq "HASH");
    }
}
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