Copper Doors can be broken by zombies
I summoned a zombie that could break doors and had it chase me. The zombie then broke down the door which made wooden door sounds. A villager was also tested and could open the copper door. This appears to be unintended behavior since the metal copper door isn't like the metal iron door. Also the copper door is categorized under the wooden doors and axe minable tags as of the time of this bug report.
Created Issue:
Copper Doors can be broken by zombies
I summoned a zombie that could break doors and had it chase me. The zombie then broke down the door which made wooden door sounds. A villager was also tested and could open the copper door. This appears to be unintended behavior since the metal copper door isn't like the metal iron door. Also the copper door is categorized under the wooden doors and axe minable tags as of the time of this bug report.
relates to
I summoned a zombie that could break doors and had it chase me. The zombie then broke down the door which made wooden door sounds. A villager was also tested and could open the copper door. This appears to be unintended behavior since the metal copper door isn't like the metal iron door. Also the copper door is categorized under the wooden doors and axe minable tags as of the time of this bug report.
(from MC-266163)
With MC-266163 being intended, perhaps it's a good time to make this event used for breaking copper doors, rather than the wooden door one.

Relate to
MCPE-176431Confirmed