use strict;
use Data::Dumper;

my @array;
for (my $i = 0; $i < 5; ++$i) {
  LABEL:
    my @y;
    push(@y, $i);
    push(@array, \@y);
    if ($i & 1) {
        ++$i;
        goto LABEL;
    }
}
print(Dumper(\@array), "\n");
[download]

$VAR1 = [
          [
            0
          ],
          [
            1,
            2
          ],
          $VAR1->[1],
          [
            3,
            4
          ],
          $VAR1->[3]
        ];
[download]

Evidently, executing a my does not replace its arguments. They hang around until they go out of scope.

Extra credit. What if

my @y;
[download]

is replaced with

my @y = ();
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I was right about one thing. Lexical variable scoping is not intuitively obvious. Fortunately, "ordinary" use is seldom so obscure.