I’m with junkyard, heights and getting old(er).
The height thing is totally irrational, illogical, obviously comes from some previous life.
Fought it all my life done all sorts of things involving height, only time it really badly affected me was once when snowboarding, I was up this ridge and set off a mini avalanche under me, left me hanging on the side of the ridge, very scary, nearly panic froze, but managed to stay calm enough to extricate myself.