My guess is that you're getting retransmissions because of dropped frames, not because there's some huge buffer in the sky.
I like "huge buffer in the sky".
That's where I imagine all my deleted data goes.
There’s one huge buffer in the sky!
The huge buffers are at the two endpoints (:->
Indicated airspeed 280kts, ground speed 470kts, FL410, the packets are trying to catch up…