All curbs are now deathtraps.
I don't know why, but with the new physics, bumps create more bumps and eventually you lose control.
Put your inside two tires on a curb. Your car will eventually flip over.
Put all four wheels on a curb. Your car will hop all wheels like a lowrider, no steering control, and go straight into a wall.
This is not a deliberate bug that only happens with crazy tuning.
This is a real tragedy that happened to me with a PP600 Corvette that I used a lot in SP/MP before the update and had a lot of trust and confidence in the tuning.