As it states in split,

If the PATTERN contains parentheses, additional list elements are created from each matching substring in the delimiter.

You can therefore get your desired result with split /(:|%|;)/, where your result list will alternate data and delimiter. If you really want to split it into two arrays, you could do something like:

my @values;
my @delims;
for (split /(:|%|;)/) {
    if (@values == @delims) {
        push @values, $_;
    } else {
        push @delims, $_;
    }
}
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