I had a few problems with Expect, so I switched over to Net::SSH::Expect. Maybe you'll have better luck with this:

#!/usr/bin/perl

use strict;
use warnings;
use Net::SSH::Expect;

use constant CMD   => 'ls -l';

$Expect::Debug => 3;
$Expect::Do_Soft_Close => 1;

my $ssh = Net::SSH::Expect->new (
          host       => "somehost",
          user       => 'someuser',
          password   => 'password',
          log_stdout => 1,
          raw_pty    => 1,
          timeout    => 5
);

eval {
      my $login_output = $ssh->login();
      if ($login_output !~ /Welcome/) {
      die "Login has failed.
      Login output was $login_output";
     }
};
        
my $spawn = new Expect;
$spawn->log_file("log.txt", "w");
$spawn->cmd(CMD);
$spawn->soft_close;

exit(0);
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Update: Fixed