One explanation is that the deeper out-of-the-money put (which remains out-of-the-money) benefits from both a fall in the underlying security and an increase in VIX. The shallower out-of-the-money put (which became in-the-money as a result of the market drop) benefits from the former, but not so much from the latter. Maybe another way to explain it is that the deeper out-of-the-money put was more mispriced to begin with.
One explanation is that the deeper out-of-the-money put (which remains out-of-the-money) benefits from both a fall in the underlying security and an increase in VIX. The shallower out-of-the-money put (which became in-the-money as a result of the market drop) benefits from the former, but not so much from the latter. Maybe another way to explain it is that the deeper out-of-the-money put was more mispriced to begin with.