Thank you for that example. When edited as shown below, it clearly highlighted the differences:

use warnings;
use v5.14;

outer1();

exit 0;

sub outer1 {
    my $hello = 'hello';

    # local *inner = sub {
    my $inner = sub {
        say $hello;
    };
    outer2();
}

sub outer2 {
    # inner();
    $inner->();
}

__END__
Global symbol "$inner" requires explicit package name at /tmp/subtst.p
+l line 20.
Execution of /tmp/subtst.pl aborted due to compilation errors.
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Compared with your example, we can show the more limited scope of the lexical form, as recommended by Laurent_R. Thank you both!