I was concerned when I couldn't find any soul sand above Y = 34 in my newly created survival map so I recreated the map in creative to look for soul sand.
I spent over an hour teleporting myself to random locations in the nether and couldn't find any soul sand over Y = 34 except in nether fortresses.
The soul sand found was always at the edge of a lava lake.
Zachary Dammann
Can confirm for 1.14.4
I was concerned when I couldn't find any soul sand above Y = 34 in my newly created survival map so I recreated the map in creative to look for soul sand.
I spent over an hour teleporting myself to random locations in the nether and couldn't find any soul sand over Y = 34 except in nether fortresses.
The soul sand found was always at the edge of a lava lake.