If you'd like to use a sledgehammer to crack a nut:

#!/usr/bin/perl

use v5.16;
use strict;
use warnings;
use PDL;

my $list = long(2,2,2,3,3,4,4);
my $rle = long(rle $list);
my $ind = maximum_ind $rle->slice('X,(0)');
say $rle->slice("($ind)");
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