The following prints

et:a)(b
eb:(a)(b)
eteb1:a)(b
eteb2:

i expected it to print

et:a)(b
eb:(a)(b)
eteb1:a)(b
eteb2:(a)(b)

were my expectations unexpected?

use strict;
use warnings;
use File::Slurp;
use Text::Balanced qw/extract_multiple extract_bracketed extract_tagged/;

my $data = '(a)(b)';
et($data);
eb($data);
eteb($data);

sub et { 
  my $data = shift;
  my @array = extract_multiple(
    $data,
    [ sub{extract_tagged($_[0], 'a', 'b', undef,)}, ],
    undef,
    1
  );
  display('et', @array)
}

sub eb {
  my $data = shift;
  my @array = extract_multiple(
    $data,
    [ sub{extract_bracketed($_[0], '()')}, ],
    undef,
    1
  );
  display('eb', @array)
}

sub eteb { 
  my $data = shift;
  my @array = extract_multiple(
    $data,
    [ sub{extract_tagged($_[0], 'a', 'b', undef,)}, ],
    undef,
    1
  );
  display('eteb1', @array);
  @array = extract_multiple(
    $data,
    [ sub{extract_bracketed($_[0], '()')}, ],
    undef,
    1
  );
  display('eteb2', @array);
}

sub display {
  my $sub = shift;
  print "$sub:";
  print $_ for @_;
  print "\n";
}