Dubai Hills villa, what plumbing issues actually come up on these newer Emaar homes and what should we stay ahead of?

You're right that age isn't the issue on a Dubai Hills villa, it's the details of a builder-grade fit-out settling in. What we typically see in the first years: mixer and tap cartridges that drip (cheap to fix, annoying to ignore), a pressure-reducing valve that needs setting so pressure is even across the house, and water heaters that are mechanically fine but set up for a generic handover, not your actual usage. The one to take seriously is any slow, concealed leak, on a fit-out this new it's usually a fitting not torqued rather than a failed pipe, but hidden water still damages finishes. None of it is dramatic if you stay ahead: get the pressure set correctly, sort dripping fittings early, and have the heater and manifolds looked over once so you know the baseline. A plumber who works across the Dubai Hills community will know these Emaar villas and what settles in early. A baseline check now beats a finish-damaging leak later.