... air traffic jams? The air is _much_ bigger than the corresponding ground.

Certainly there'd be density _at_ take-off and landing, but even that's manageable by having e.g. arrival/departure locations at multiple heights.

It also seems vanishingly unlikely (at this point) that we'd have EVTOL that's not fully autonomous, further reducing the odds of this - ~perfect and coordinated driving, as well as foreknowledge of what's happening between you and the arrival location drastically reduces traffic.