use strict;
use warnings;
use feature qw /say/;

my %hash = (a => 1, b => 2, c => 3, d => 2, e => 5, f => 3);
my %HoA;
for my $key (keys %hash) {
	my $value = $hash{$key};
	push @{$HoA{$value}}, $key;
}
for my $key2 (keys %HoA) {
	my @keys = @{$HoA{$key2}};
	say "Keys @keys have the same value: $key2 ";
}

##</code><code>##

$ perl  reverse_hash.pl
Keys a have the same value: 1
Keys c f have the same value: 3
Keys b d have the same value: 2
Keys e have the same value: 5

##</code><code>##

0  HASH(0x60025cbb8)
   1 => ARRAY(0x60006f210)
      0  'a'
   2 => ARRAY(0x600462490)
      0  'b'
      1  'd'
   3 => ARRAY(0x60048d1b8)
      0  'c'
      1  'f'
   5 => ARRAY(0x600495808)
      0  'e'