A lexical (my) variable get cleared when exiting the tightest lexical scope (curlies or file) in which it is found.

sub f {
   my $x = ...;
   {
      my $y = ...;
      ...
      # $y cleared here.
   }
   ...
   # $x cleared here.
}
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It doesn't matter how the scope is exited. It'll get cleared on return, die, next, etc.

You obviously didn't read the documentation for $|.