Just for fun, throwing a few more possible solutions out there:

use warnings;
use strict;

while (1) {
  print "Answer: ";
  chomp( my $answer = <STDIN> );
  
  use Quantum::Superpositions 'any';
  # OR
  #use Perl6::Junction 'any';
  warn "not yes 1" unless $answer eq any('y','Y');
  
  warn "not yes 2" unless $answer =~ /^(y|Y)$/;
  
  # be a little more flexible:
  warn "not yes 3" unless $answer =~ /^y(es)?$/i;
  
  last if $answer=~/quit|exit/i;
}
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