Backporting a 1.21.1 loot table to 1.20.5

From what it seems, every entity loot table in 1.21.1 with looting doesn't work in 1.20.5. I took a look at the 1.20.5 code, and the only difference was that the "enchantments" field was gone, but that doesn't fix the issue. So, how do I backport the loot table?