The recipe for a copper trapdoor is made from six blocks of copper, and only gets two or three units. In my opinion they should be from the copper item, like an iron door, and the other oxidation versions will be available after the door is oxidized.

Steps to restore:
1. Go to Minecraft Preview.
2. Take six copper blocks (no matter what oxidation state.)
3. Place them as you would place a wooden trapdoor or wooden door
.

Expected results:
Three copper doors or two copper trapdoors will be created.