In the latest snapshot (24w33a) the rarity of the items have been changed, but the netherite tools and armors are still got the common rarity while one of the guidline for the rarity change was this: "Any item or block which can be crafted must inherit the highest rarity of its crafting ingredients", but it seems like that is not applied to when using the upgrade template or smithing templates.
 
What was expected: 

• Netherite tools and armors inherit the upgrade template's rarity

• Every armor inherit their applied armor trim's rarity

What is happening:

• Netherite armors and tools stay have the common rarity
• Any armor that has an armor trim applied, still has the common rarity