Silk Touch cannot be combined with Looting or Luck of the Sea

The bug

It is impossible to combine the "Silk Touch" enchantment on an anvil with any item with the "Looting" or "Luck of the Sea" enchantment or vice versa.

Code analysis

20w08a, Mojang names

net.minecraft.world.item.enchantment.LootBonusEnchantment.checkCompatibility(Enchantment) (which is used for "Fortune", "Looting" and "Luck of the Sea") prevents combining it with "Silk Touch".

Note that it would probably possible to remove that method override because compatibility is checked reflexively (see Enchantment.isCompatibleWith) and UntouchingEnchantment (used for "Silk Touch") already verifies that it cannot be combined with "Fortune".