What gets damaged when fuel tank over-filled?

[B.L.E]

@the_same_mountainbik

Recognize that the charcoal canister that everyone is alluding to is the only method your gas tank has of breathing in to fill the void left as the gas is pumped out. Should it become saturated, the tank will be unable to breath in, the pump will struggle, the car may stall, and you might experience premature pump failure.

And the gas tank itself can collapse from the suction.