@Robert Taylor good question, and honestly it's one of the more interesting edge cases for this hardware.
The 50km figure is drone-to-drone with both elevated and no ground reflections — so your setup is closer to the man-to-drone scenario (15-20km range) since you've got one end on a ground vehicle. That's still very usable, just worth calibrating expectations against that number first.
On the Doppler side — BLE operates at 2.4GHz, and at the speeds a ground vehicle or typical drone is doing, the Doppler shift is pretty negligible. You'd need relative velocities in the hundreds of km/h to start causing meaningful frequency offset that the receiver can't compensate for. The bigger practical concern in your setup is antenna orientation, not Doppler. When both platforms are moving and turning, you'll naturally hit nulls in the radiation pattern depending on antenna mounting — that's where you'll feel link margin fluctuate more than from any Doppler effect.
If you're mounting on the ground vehicle, getting the antenna up high and clear of the vehicle body makes a noticeable difference. On the drone side, orientation relative to the ground node changes a lot during aggressive maneuvers, so mounting position matters there too. The RF front-end itself handles motion gracefully — it's the geometry that'll be your variable, not the hardware hitting some speed threshold.
