I agree with MERXLE, taking at least an hour for an Oxidized Copper Golem to become a statue is an extremely long amount of time. It’s also out of parity with how it works in Bedrock Edition, where once a Cooper Golem is oxidized, it takes about 10 seconds to become a statue.
Confirmed as of 1.21.2-RC1.
In fact, if you time submerging underwater as the animation plays and reverses, it is possible to catch the animation on a frame where a bubble is missing in the graphic.
Confirmed as of 1.16.3
Confirmed in 1.21.111, now with an even more egregious example. Spruce shelves, which are designed to match with their respective stripped logs, are colored properly, causing this to happen.