As you're making incremental improvements, here's another. Just a little Sunday morning exercise to get the mental juices flowing. :-)

Creating the four new_* key-value pairs and doing four // checks, always produces the same result: you only need to do that once. I kept your code up to and including my $add_in = ..., then added these two statements:

my $add_hashref = {
    map +('new_' . $_ => $add_in->{$_} // ''),
        grep $_ ne 'status', keys %$add_in
};
%$_ = (%$_, %$add_hashref) for @$data;
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The Dumper output is the same as yours; at least with a fairly thorough visual check, and bearing in mind that key-value pairs are unordered in a hash.