Last I checked, the evidence was unclear whether it's the mate or the temperature it's consumed at. Which is weird to be because I thought mate was brewed at lower temperature compared to coffee (70°C). Either way, the WHO recommends you don't take your beverages too hot:
Drinking alcohol increases the risk of mouth cancer, pharyngeal (upper throat) cancer, oesophageal (food pipe) cancer, laryngeal (voice box) cancer, breast cancer, bowel cancer and liver cancer.
But that doesn't really seem to slow anyone down.
Sure, but assuming the mate drinkers are also drinking alcohol, it may have a synergistic effect and increase risk much beyond either alone, like tobacco and alcohol do with each other. Pure speculation though.