A recently built house has different plumbing characteristics from an older one, and they are worth knowing about.
Fixtures and appliances are usually under manufacturer warranty for a period, so it is worth checking warranty terms before arranging a repair, because some warranties require the work to be done in a particular way to remain valid.
Modern homes often run more water using appliances simultaneously than older designs anticipated, which is where flow rate rather than pressure becomes the limiting factor. Continuous flow hot water units in particular have a maximum flow they can heat, and running two showers and a dishwasher at once can exceed it.
New homes can also settle in their first years, and minor movement occasionally shows up as a leak at a joint. That is not a defect in the plumbing so much as a consequence of the building bedding in.
If a hot water system is leaking, making unusual noises, or delivering water hot enough to scald, switch it off at the isolation point if you can do so safely and call a licensed plumber. Tempering valves and pressure relief valves are not do it yourself items, and a failed relief valve can be dangerous.
