I'd like to see a 'stricter taint'.

It would mark everything as tainted, and expand the scope of things that blow a taint error. For example:

use stricter qw(taint);
use foo qw(frob);
use bar qw(clam);
my $blah = frob("something");
clam($blah);
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$blah would be tainted because we don't trust the foo module to return something rational, and clam($blah) would blow an error because we don't trust the bar module, so we don't know what clam does, and we just passed it something tainted.