Re^3: why is $1 cleared at end of an inline sub?

The linked documentation explains it. Dynamic scope propagates inside blocks, but not outside.

my $s = 'abcdefg';
$s =~ m{abc(de)(fg)};
my $output = do { sprintf "1=%s, 2=%s", $1, $2  };
print $output;  # 1=de, 2=fg
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map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]