Note that your code doesn't follow the original with regard to the index. You only increase the index if the if branch is evaluated. You need to increase $i outside the if. I'd probably rewrite it to this though:

my @fields = qw/ ... /;
for (0 .. $#fields) {
  get_updates($objects[$_], $fields[$_], $result_ref->{$fields[$_]}
    if defined $result_ref->{$fields[$_]};
}
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A structure like that doesn't invite to get things out of sync.

ihb