Generally, it’s safest to assume that any waterproof material is non-breathable. If you exert yourself in them, you sweat and trap that sweat inside the membrane, often guaranteeing to soak yourself even if the rain lets up. Windbreakers with some basic spray on water resistance just work better (which is to say, not great).

Best thing overall is to just wear synthetics that dry very quickly (pair with waterproof bag for your backpack contents - trash compactor bags are amazing for weight efficiency)