So I just want to point out that if you fly your flying mount over the entrance to the Farshire Mine in Borean Tundra, you get dismounted. Height doesn’t seem to matter.
The first time, I thought it was a random glitch or that I bumped something, but then it happened on a separate character in the same spot. First time I fell to my death, the 2nd time, I got lucky and survived.
Same with the tunnel/mine in storm peaks to Brunn village, from the first quest area. Died chasing vyragosa
Same thing with the Transitus Shield area in Coldarra, as well as the main room for EoE, The Nexus, and The Oculus’ “dismount hitbox” extending above the room, even affecting the platform of the questgiver Corastrasza, making getting to her certain death without a parachute.
Overall, it seems this has to do with certain “indoor” areas extending through the air. If it’s instant and there’s no warning before being kicked off your mount randomly, good chance it’s this recurring bug.