Soft pedal, grinding, pulling, smoke off a wheel — brakes are the one problem you don't drive another mile on. The right answer comes to you.
A 20,000 lb motorhome with compromised brakes on a 6% downgrade is not a story you want to be in. Brake symptoms on RVs escalate fast because the loads are high and the service intervals are long. If something changed about how the rig stops — today, not at the end of the trip — get it looked at where it sits.
RIG mechanics do brake work on heavy rigs every day — motorhome brakes are the same systems. A mobile mechanic can replace pads, free a stuck caliper, or diagnose air systems at your location, and tell you straight if it genuinely needs a shop. Chat the symptom now; keep the rig parked until someone who does this daily has eyes on it.