If matter falling past the event horizon is converted to energy by acceleration to the speed of light, in orbit just beneath the event horizon, then a shrinking event horizon could be releasing some energy (photons) as it shrinks, and depending on that ratio of mass-energy-mass relationship, perhaps it would also drag more mass/energy out with it, shrinking the event horizon even more and starting a cascade that would tear the black hole apart.

(reverse frame-dragging?)

Just a 2-bit thought, and as most are; probably wrong.