It was only reduced from 10000 to 8000 compared to the Steam version. On top of that, shields can reduce crash damage by 20% of their own max HP (basically this means Czars/Ahwassas crashes can only kill 3600 HP SMD through shields).
@Kilatamoro is correct in that it's like a normal AoE that gets absorbed by shields. I did write some code where crash splash damage ignores shields, since it is reduced by shield max HP already, but the issue is that if the unit crashes right outside a shield it deals 8000 damage straight through the shield, which isn't fixable.