 Unfortunately , recent studies indicate that such advanced methods may suffer from adversarial attacks, i.e., they may lose effectiveness when only a small fraction of links are purposely changed.
<clarity>  Unfortunately , recent studies indicate that such advanced methods may suffer from adversarial attacks, i.e., they may lose effectiveness when only a small fraction of links are purposely changed.
 Unfortunately , recent studies show that these advanced methods may suffer from adversarial attacks, i.e., they may lose effectiveness when only a small fraction of links are purposely changed.