When Gita 5.18-25 talks about brahma-nirvana, why does Prabhupada say that impersonalism is troublesom?

From Mithilesh P

The verses 5.17-5.24 (BG) bhagvan Krishna talks about “brahmabhuta” and “brahmanirvana” and says that such a person attains supreme. Why then srila prabhupada talks about the fall of impersonalists and that they reach supreme destination after many births.