Dampness is most likely sweat not leaks. Test for leaks when you’re not sweating your balls off. I’m a skinny guy and even in breathable waders, I’m soaked after a summer wading session. I had waders leak before, and there is clear distinction.
But if you are certain it’s leaks, I recommend compass 360 waders (I think slumberjack now?). Relatively inexpensive and fairly durable- had a pair for over two seasons (back when I fished a lot more) until I ripped them on a barbed wire.
Probably condensation as breathable waders don't exactly breath well anyways, especially if it's warm in my experience. If they were leaking you would have soaked feet unless that is you sweat a lot. I filled up my last pair with water and marked leaks with a sharpie. They were leaking in the booties only so it didn't take much water, might not be the best way to check, stresses the seams. They got really bad so I just got a new pair, I'll send the worn ones back to see if they'll replace the booties. I guess neoprene wears out, I read it has something to do with it being compressed/worn and eventually causes water to pass through it.
Sweat. Condensation. If you have a leak you will know it. Im always repairing waders, especially from thorns. Good trick is reverse your waders and garden hose partially fill them with water. You can see the leaks and after drying them repair them with aquaseal.