When a Loyalty Trident is thrown, it returns to the inventory according to the order that items are usually picked up in; hotbar first - but not necessarily the slot it was thrown from, and then main inventory if there's room. If only the offhand is empty, the trident will not return to the inventory at all. This causes the player to have to engage in pointless, makework inventory management during combat.

I propose that Loyalty behaves as following, which would incidentally close most issues relating to the enchantment;

A Trident enchanted with Loyalty should remain in the slot it is used from, like a Riptide one. Instead, a duplicate with the Loyalty enchant removed and the "pickup" tag set to either 0 (cannot be picked up) or 2 (only creative players can pick up) should be thrown. The Trident remaining in the inventory should go on cooldown like an Enderpearl, the duration being determined by the level of Loyalty.

This solution uses behaviours and interface elements already present in the codebase and familiar to users, and would provide a more consistent, streamlined experience.