There are a few problems with your regex, but your first is the extraneous use of .* as delimiters. The one in the second line of your regex is greedily matching everything else in your line and therefore none of the other sections are able to match.

I would advise that you use Text::CSV to progress the csv file and then use a regex to split apart each section. However, forgoing that, something like this would work as well.

use strict;

while (my $line = <DATA>) {
    chomp $line;
    
    my %vals = ($line =~ m{(\w+)=([^,]*)}g);
    
    print "one: $vals{one}, two: $vals{two}, three: $vals{three}, four
+: $vals{four}, five: $vals{five}\n";
}

1;

__DATA__
one=1,two=2,three=3,four=4,five=5
one=1,three=3,five=5
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