Discolorations flow rate regulators

Hello everyone,

we have 2 heating circuit distributors in the house, one in the basement and one in the attic. In the basement, all the flow regulators are clear and readable. In the attic completely discolored. Why, how come, why? Can it be remedied? Does it have negative effects on the heating circuits in the attic?

It's the same with us, I also have no explanation

Something seems to be oxidizing somewhere somehow?

Exactly. For example, towel holders in the bathroom? Everything remains clear with us.

Yes, but it only runs with an e-cartridge, completely unaffected by the heating circuit.

Then I would keep searching, otherwise you will soon see nothing anymore. Just Google it, you're not the first.