Tafsir of An-Najm 53:54

In this there is an intensification of the punishment and a generalization of what afflicted them from it, because the relative pronoun (ma) is among the forms of generalization.

The doubling (tashdid) in ghashaha (فغشاها) may be for the purpose of making the verb transitive, in which case ma (ما) is the second object, and the subject is His—Exalted is He—pronoun. It is also possible that it is for the purpose of intensification and hyperbole, in which case ma (ما) is the subject.