Using Item.of("diamond_sword", "{damage:50}") as an example:

• .weakNBT() If the item's NBT contains {damage:50}, it can be used. Examples:
  • ✅ {damage:50}
  • ✅ {damage:50, display:"Sword"}
  • ❌ {display:"Sword"}
• .strongNBT() If the item's NBT only contains "{damage:50}", it can be used. Examples:
  • ✅ {damage:50}
  • ❌ {damage:50, display:"Sword"}
  • ❌ {display:"Sword"}