The reason why copper changes colour is because they go through a natural process called patination, where it reacts with oxygen, moisture, and other elements in the environment to form a protective layer of corrosion.

With this,we should be able to speed up the corrosion if there is water nearby.This is because even when you place the copper blocks 4 blocks apart to increase the speed,it is still to slow.

Mojang can implement this with several ways. (A)Minecraft Zombie Villagers get cured faster because there is blocks like iron bars and beds nearby.So,we can use the same idea for copper oxidation if there is any waterlogged blocks or water blocks nearby.

(B)How dirt becomes mud by using a water bottle.With this,we can use the same feature for copper oxidation so that each water bottle used on the block takes it to the next stage of oxidation.

Personally I think A is the best one,but overall this is just a fun idea for a bit of quality of life update.

Tell me what you guys think!