Evacuation of Earth-38

"Your universe is no more. Of 7.53 billion, 3 billion souls made it to Earth-1 on the armada of ships. I calculate 1 billion souls survived due to his noble sacrifice."

- Mar Novu to Kara Danvers

Earth-38 was evacuated after the quantum towers failed to hold off the antimatter wave. In the end, 3 billion citizens of Earth-38 were successfully evacuated. At least a billion were due to Oliver Queen's heroic efforts and refusing to abandon the defense of the quantum tower until he was overpowered and beaten to death by the Shadow Demons.

History
On December 10, 2019, Harbinger gathered select heroes of Earth-1 to Earth-38, which was being wiped out by a wave of antimatter. The quantum towers which Mar Novu placed on key Earth's during the dawn of time helped hold off the antimatter for a short while. However, Mobius's army of Shadow demons were quick to thwart their plans.

Alex Danvers looked to Lena Luthor to build a big enough transmatter portal which the agreed to despite their differences.

In defense of the quantum tower, the heroes of Earth-1 fought the shadow demons from a fortified position while Kara and Clark fought the shadow demons from outside. They manage to hold them off for a short while, but the quantum tower was struck and the skies were red once more. Kara and Clark were able to make the tower operational long enough for the evacuation to take place.

Meanwhile, J'onn gathered an armada ships to board the citizens of Earth-38, including one left by the Legion.

The heroes took one final stand on the roof of the building. However, the Monitor told them the battle was lost and to save their resources for future battles. While the heroes continued to fight, the Monitor sent each one to Earth-1. When he told Oliver it was time, Oliver refused to leave until everyone was evacuated. As the Monitor tried to send Oliver back to Earth-1, Oliver fired a specialized arrow that manage to temporarily disable him. Oliver continued to fight off the shadow demons until he was out of arrows. As the shadow demons swarmed around Oliver, he took one final stand, dropping his bow and charged towards the army. As Earth-38 was hit with the antimatter wave, the Monitor brought Oliver back to Earth-1 but had already sustained fatal injuries.

In the end, there was an estimated 3 billion evacuated, with a billion due to Oliver staying behind and continuing to fight off the shadow demons to his last breath.

Unfortunately, Oliver's sacrifice was in vain as Mobius was ultimately successful in destroying the multiverse, including Earth-1, meaning the Earth-38 survivors were still doomed and were killed.