Related to: MC-200991.

Jumping on soul sand occasionally uses durability of Soul Speed boots despite the fact that you are not moving horizontally.
Since you are not walking on the soul sand blocks, you should not take durability.
Doesn't work with soul soil.
This probably caused by soul sand not being a full block.

Steps to Reproduce:

• Stand on some soul soil or sand.
• Give yourself some boots enchanted with soul speed and equip them.

• /give @s minecraft:leather_boots{Enchantments:[{id:"soul_speed",lvl:3}]}

• Without moving, start jumping constantly.
• Look at the durability of your boots after you've jumped several times.
• →  Notice how jumping on soul sand/soil whilst wearing soul speed boots consumes durability.

Expected Behavior:
Jumping on soul sand/soil whilst wearing soul speed boots would not consume durability as you are not moving.