I experienced the same situation about 3 years after I acquired my XT276. The hot water side for the tub/shower was super low flow. Everything was fine before.
I removed the wall tub faucet fixture to see behind the wall and discovered when the factory installed the water lines, the hot water side was to long and after a few years, the line had kinked reducing the water flow.
Simply re-positioning the line and securing it relieved the kink and all has been fine since. It's possible your situation is similar.
2012 Fun Finder XT 276 Toy Hauler & Harley Davidson Ultra Classic with Condor wheel chock
2014 Dodge Ram 2500 AT 4X4 Crew Cab 6.4 L Hemi, 373 gears, tow package, Rambox option, Revolver X2 tonneau cover, Equal-I-zer anti-sway hitch.