With 1.20.5 coming and introducing many changes to items, as well as Neoforge overtaking Forge, I expect some mod code might need to be largely rewritten. With that in mind, I'd like to suggest making designs have their own item IDs.
Cons:
Probably harder to code.
Pros:
Fixes Designs appearing in JEI or other similar mods;
Streamlines Design insertion into loot tables;
Allows Designs to be individually tagged;
Makes Designs more compatible with other modded systems which might not support checking NBT or 1.20.5+ components.
With 1.20.5 coming and introducing many changes to items, as well as Neoforge overtaking Forge, I expect some mod code might need to be largely rewritten. With that in mind, I'd like to suggest making designs have their own item IDs.
Cons:
Pros: