#!perl

use 5.012; # strict, //
use warnings;

my $favorites = join '~~~', map("t|k|$_", 1..30); # create data for SSCCE
print "initial favorites: $favorites\n";
print "="x40, "\n";
#####################################
{
    print qq#This was my original: it doesn't quite work, because the 25th will contain _all_ the remaining text \n#;
    my @favs = split /~~~/,$favorites,25;
    my $favnums = "";
    foreach (@favs){
        next unless defined;
        printf "fav: %s\t", $_;
        my ($favtitle,$favlink,$favnum) = split /\|/,$_;        # you had the wrong split expression; you only need one pipe in the split
        $favnums = $favnum . "," . $favnums;
        print "partial favnums: $favnums\n";
    }
    print "WRONG FOR 25+: favnums: $favnums\n";
    print "="x40, "\n";
}
#####################################
{
    print qq#This tweaks the limit\n#;
    my @favs = split /~~~/,$favorites,26;
    $#favs = 24 if @favs>25;    # clips it to 25, so it throws away the 26th entry if there was one
    my $favnums = "";
    foreach (@favs){
        next unless defined;
        printf "fav: %s\t", $_;
        my ($favtitle,$favlink,$favnum) = split /\|/,$_;        # you had the wrong split expression; you only need one pipe in the split
        $favnums = $favnum . "," . $favnums;
        print "partial favnums: $favnums\n";
    }
    print "CORRECT LIMIT+TRIM: final favnums: $favnums\n";
    print "="x40, "\n";
}
#####################################
{
    print qq#This uses the counter\n#;
    my @favs = split /~~~/,$favorites;
    my $favnums = "";
    foreach (@favs){
        state $counter = 0;
        last if $counter++ >= 25;
        printf "fav: %s\t", $_;
        my ($favtitle,$favlink,$favnum) = split /\|/,$_;        # you had the wrong split expression; you only need one pipe in the split
        $favnums = $favnum . "," . $favnums;
        print "partial favnums: $favnums\n";
    }
    print "CORRECT COUNTER-based: final favnums: $favnums\n";
    print "="x40, "\n";
}
__END__
initial favorites: t|k|1~~~t|k|2~~~t|k|3~~~t|k|4~~~t|k|5~~~t|k|6~~~t|k|7~~~t|k|8~~~t|k|9~~~t|k|10~~~t|k|11~~~t|k|12~~~t|k|13~~~t|k|14~~~t|k|15~~~t|k|16~~~t|k|17~~~t|k|18~~~t|k|19~~~t|k|20~~~t|k|21~~~t|k|22~~~t|k|23~~~t|k|24~~~t|k|25~~~t|k|26~~~t|k|27~~~t|k|28~~~t|k|29~~~t|k|30
========================================
This was my original: it doesn't quite work, because the 25th will contain _all_ the remaining text 
fav: t|k|1	partial favnums: 1,
fav: t|k|2	partial favnums: 2,1,
fav: t|k|3	partial favnums: 3,2,1,
fav: t|k|4	partial favnums: 4,3,2,1,
fav: t|k|5	partial favnums: 5,4,3,2,1,
fav: t|k|6	partial favnums: 6,5,4,3,2,1,
fav: t|k|7	partial favnums: 7,6,5,4,3,2,1,
fav: t|k|8	partial favnums: 8,7,6,5,4,3,2,1,
fav: t|k|9	partial favnums: 9,8,7,6,5,4,3,2,1,
fav: t|k|10	partial favnums: 10,9,8,7,6,5,4,3,2,1,
fav: t|k|11	partial favnums: 11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|12	partial favnums: 12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|13	partial favnums: 13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|14	partial favnums: 14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|15	partial favnums: 15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|16	partial favnums: 16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|17	partial favnums: 17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|18	partial favnums: 18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|19	partial favnums: 19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|20	partial favnums: 20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|21	partial favnums: 21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|22	partial favnums: 22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|23	partial favnums: 23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|24	partial favnums: 24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|25~~~t|k|26~~~t|k|27~~~t|k|28~~~t|k|29~~~t|k|30	partial favnums: 25~~~t,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
WRONG FOR 25+: favnums: 25~~~t,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
========================================
This tweaks the limit
fav: t|k|1	partial favnums: 1,
fav: t|k|2	partial favnums: 2,1,
fav: t|k|3	partial favnums: 3,2,1,
fav: t|k|4	partial favnums: 4,3,2,1,
fav: t|k|5	partial favnums: 5,4,3,2,1,
fav: t|k|6	partial favnums: 6,5,4,3,2,1,
fav: t|k|7	partial favnums: 7,6,5,4,3,2,1,
fav: t|k|8	partial favnums: 8,7,6,5,4,3,2,1,
fav: t|k|9	partial favnums: 9,8,7,6,5,4,3,2,1,
fav: t|k|10	partial favnums: 10,9,8,7,6,5,4,3,2,1,
fav: t|k|11	partial favnums: 11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|12	partial favnums: 12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|13	partial favnums: 13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|14	partial favnums: 14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|15	partial favnums: 15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|16	partial favnums: 16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|17	partial favnums: 17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|18	partial favnums: 18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|19	partial favnums: 19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|20	partial favnums: 20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|21	partial favnums: 21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|22	partial favnums: 22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|23	partial favnums: 23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|24	partial favnums: 24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|25	partial favnums: 25,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
CORRECT LIMIT+TRIM: final favnums: 25,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
========================================
This uses the counter
fav: t|k|1	partial favnums: 1,
fav: t|k|2	partial favnums: 2,1,
fav: t|k|3	partial favnums: 3,2,1,
fav: t|k|4	partial favnums: 4,3,2,1,
fav: t|k|5	partial favnums: 5,4,3,2,1,
fav: t|k|6	partial favnums: 6,5,4,3,2,1,
fav: t|k|7	partial favnums: 7,6,5,4,3,2,1,
fav: t|k|8	partial favnums: 8,7,6,5,4,3,2,1,
fav: t|k|9	partial favnums: 9,8,7,6,5,4,3,2,1,
fav: t|k|10	partial favnums: 10,9,8,7,6,5,4,3,2,1,
fav: t|k|11	partial favnums: 11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|12	partial favnums: 12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|13	partial favnums: 13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|14	partial favnums: 14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|15	partial favnums: 15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|16	partial favnums: 16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|17	partial favnums: 17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|18	partial favnums: 18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|19	partial favnums: 19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|20	partial favnums: 20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|21	partial favnums: 21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|22	partial favnums: 22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|23	partial favnums: 23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
fav: t|k|25	partial favnums: 25,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
CORRECT COUNTER-based: final favnums: 25,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,
========================================