Copper deficiency is more likely to strike in areas of the world with low endogenous copper in their water supply or they are using RO or DI for brewing. There have been many cases where sulfurous aroma is rapidly eliminated by allowing wort or beer to contact elemental copper. So having a low level of copper in your brewing water is a good thing. Its when its excessive that I can see this Fenton's reaction having a negative effect on beer.
I see that there are simple water test kits for copper content. I wish I knew what levels are appropriate or excessive. Sounds like this is a task for a brewer that used to have sulfur problems and has added some copper to their system to resolve it. A test of the raw water and a test of water or wort from their system, might give us some insight. Who in the forum has this condition?