The Suspicious Sand can definitely brush out a Mob Enchant Book, but this only happens when the loot table of the Suspicious Sand is that of a Desert Pyramid. The corresponding command to generate such Suspicious Sand is:
/setblock ~ ~-1 ~ minecraft:suspicious_sand{BlockStateTag:{},LootTable:"minecraft:archaeology/desert_pyramid"}
I don't know if this is intentionally designed or a bug.
Minecraft version: 1.21.1
mod version: 20.8.0