When you write the expression...

$test_hash{$key1}{$key2}
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... the key1 hash value must be auto-vivified as a hash reference for a dereference to happen. However, exists will not auto-vivify the key2 hash-key which is actually being tested for.

   MeowChow                                   
               s aamecha.s a..a\u$&owag.print