I’m at a loss… not sure what to do now…

I have hot water flowing from water heater, but lukewarm water at all faucets in house (even newly replaced per lines in bathroom remodel)…

I have a tankless water heater, it has been flushed till clear of sediment and debris, replaced the flow sensor (confirm unit is recognizing flow), cleaned flame rods, and confirmed that hot water is flowing out (release valve is hot, and pipes are hot to the touch).

water coming from faucets has good pressure, but is lukewarm (at best). Tolerable compared to cold water only, but not the 120 degrees it’s set to…

I thought maybe sediment got into my valves, but that would impact flow/pressure would it not?

I’m at a bit of a loss… what can cause this?