Thanos' snap with death wave combined by Darkseid's Anti-Life Equation erased half of Universe's populace, along with Ultimecia's time compression in arrow of time that is irreversible and there might be no way back anymore.
Half of the population were gone. The surviving half were affected by Darkseid's Anti-Life Equation.
Half of the stars of the Universe were erased, but surviving half were black holes.
Thus the Cataclysmic and Apocolapyic era began.
Half of the digital data were deleted upon Thanos' snap, thus the remaining half were corrupt and or faced rebooting.
Decay rate of every living and non-living thing doubled under Thanos' snap and Darkseid's Anti-life Equation.
Cancer and disease rates were sped up double.
Life expectacy was halved.
Thanos and Darkseid became Thanoseid, an epitome of pure evil.