Are %repl's keys regexp or text?

If they're regexp, your lookup won't work.

If they're text, they should be converted to regexps before being included in the combined regexp.

my $search = join "|", map { qr-\b\Q$_\E\b- } keys %repl;
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Of course, you're better of using Regexp::List.

use Regexp::List;
my $search = Regexp::List->new->list2re(keys %repl);
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