The cost of an article in an open-access journal is approximately 2000 and 3000 euros/USD (even more in some cases). However, such journals could hardly obtain such quality without the "free" peer review of many researchers. I am not satisfied with discounts or compensation. If these publishers (whose name is on everyone's head) charge such amounts and we, as reviewers, are part of the process of such quality, where is our money?
Do you agree? So, would you only review these journals if you were paid? I certainly would. Don't give away your work this way.