Does the scholarly disagreement regarding the disbelief of one who abandons prayer include someone who feigns prayer without believing in it or performing it, such as one who bows and prostrates without recitation or glorification? And does the ruling differ if he is an imam who recites while not believing that he is praying?

It is not permissible to pretend to pray. If the Imam does not perform the prayer well, the ma'mum (follower) may intend to pray alone and pray individually, even if he follows the Imam in the movements. However, if the one pretending to pray is an Imam, this is even more reprehensible because it exposes the prayer of those behind him to invalidation according to those who believe in the absolute linkage of the ma'mum's prayer to the Imam's prayer. The Shafi'is have a view that the ma'mum's prayer is valid in this case, which is the choice of Abu Muhammad ibn Hazm.