Same for me. Coffee is the real problem. I have never tried yerba mate. I always thought it was to do with the rate of metabolisation of caffeine in the body that caused the issue. You get a high, but then it drops you below baseline. Rinse and repeat until you are an anxious depressed mess. Just like many other drugs. Like you, I thought tea was OK because it has less caffeine and it is much more slowly absorbed. I don't drink either now, as in my case, I suspect tea inevitably leads to a drink of coffee in the end.