In 2014 we had a big leak in the back of the toilet. Either at the factory or dealer they had used a short white vinyl clad type water hose that ws stiff and put a curl in it to the toilet from the fitting on the wall. The fitting which was plastic or some polymer finally broke. Lucky to find a small RV Dealer who had a fully equipped Mobile Tech who replaced it with proper tubing and fittings.
All sorts of water pipes and tubing out there that work as long as they aren't under undue stress. I'm glad we weren't connected at the time to a 85 lb or higher pressure faucet.