Melasma?
Several years ago "all of a sudden" I began noticing more and more "freckles" on my face, now, I'm Hispanic with a permanent tan, lol! Maybe because I was going out in the sun frequently and didn't always remember to protect my face they soon multiplied and became so apparent I had to begin to wear foundation whenever I went out, which I didn't need before (people always commented positively on my skin), I then found an OTC bleaching cream that worked pretty well and fast, they didn't all go away but those that remained faded away a lot, but I've noticed how they do tend to darken again when I stop the cream for a good while...
But I saw my sisters have the same spots and I read it often comes with "age" (we were all over 45), that it can be hormonal, blah, blah, I even read it could be due to having fungi inside, which I suspected for myself. In any case, my older sister had had all kinds of hormonal problems which started with a pituitary tumor that was removed in 2000 and got more severe then, at least for a while, and the younger one has fibromyalgia and has also gone through a LOT of stress, for all I know she may have been suffering from AF all these years too.
What I can see is that the nutritional demands stress imposes in our bodies are often impossible to meet and thus we come into an unbalanced state in which many things can go wrong, so possibly it's stress and the huge breakdown of tissue and toxins originated during repeated “alarm” stages, plus all the environmental insult our bodies already suffer, which makes it impossible for our liver/kidneys to keep up and then not only copper but other “things” build up too.
It's just too many things to consider to blame it on just one, for example, those of us who have “gut disbiosis” and overgrowth of Candida (and heaven knows what else), also have the overload of their toxins inside our bodies. Two years ago when I was told that my liver enzymes were elevated (althought it was really not the first time but the one before, several years earlier, the doctor and I attributed to prescription drugs I was on at the time, which except for female bio-identical hormones, I stopped) I thought it was due to Candida and fungus, now... go figure!