There is a section just after leaving the front walls (right around where Geiger spawns iirc) of the House of Constructs that dismounts you while in air.
I came upon an insight about this. The hard way.
At coordinates 36.4, 36.4 Xandria the Kyrian Paragon of Courage is hovering at height. She has a dismount column around her extending out about 30 yards and an unknown amount above and below her. She’s there for Chapter 5 of the Kyrian campaign, where Bastion assaults the House of Constructs.
She hovers there but is actually mountable if you are lucky or quick of reflexes, and if you manage to engage her she’ll carry you down to the ground just like in the assault quests of Chapter 5, depositing you in the southwest corner of the Separation Chamber area.
So. Unphased quest crap that may send you to your death if you’re not ready for it.