The arrow is optional after a hash key or array index, it is mandatory only after the scalar containing a reference. Thus,

$h_ref->{key};
$a_ref->[1];
$h_ref->{key}{deeper};
$h_ref->{key}[2];
$a_ref->[0][1];
$a_ref->[1]{inside};
$arr[0][1];
$hash{key}{deeper};
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are all OK.