Update: After enabling warnings in the command line, I got the same warnings in 5.39.4. So, disregard this node.

You don't show enough for us to answer. I tried the following in two different versions of Perl (one of them older and one newer than 5.36).

I saved the following script as 2.pl:

#!/usr/bin/perl
use strict;
use feature qw{ say };
use warnings;

my $x = 10;
for my $i (1 .. 10) {
    $x += $i;
}
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I then ran

perl -d 2.pl
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using both the Perl versions.

5.26.1:

  DB<1> @lines=@{"_<2.pl"} ; for my $i (0 .. $#lines) { CORE::say $lin
+es[$i] == 0 }
1
1



1



1
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5.39.4 (blead):

  DB<1> @lines=@{"_<2.pl"} ; for my $i (0 .. $#lines) { CORE::say $lin
+es[$i] == 0 }
1
1
1
1
1
1



1
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The output is different, but there's no warning.