It's possible the water line is kinked somewhere.
I lost hot water in my shower after a few years... plenty of cold but very little hot water & made for uncomfortable showers.
I removed the wall faucet/diverter and found the hot water line was longer than required and it have moved during camper use and eventually kinked. I was able to re-route the line and secure it so easy fix. Then just reinstalled the faucet set in the wall and all has been perfect since.
Since yours is new and just purchased, I'd return it to the selling dealer for warranty repair.
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.