gradual loss of pressure

We just had our home replumbed. Now I have one outside faucet that has a gradual loss of pressure.

I connect a sprinkler to a hose, turn on the water to the point that I am watering a 4' x 5' area. I return in approx 30 minutes and there is no water pressure at all. I turn the water up more so that I am watering the same area, return in 30 minutes and again no pressure. there is NO water being turned on anywhere in/outside the house.

So far today I estimate I have done this 8 times and the problem persists. The contractors are still here, and off the top of their head, they can't explain why this is happening.

Could it be a bad (new) faucet?
Could there be a leak under the house?

What is your water pressure at your hose bib?

I don't know what the pressure is at the hose bib. They are going to measure it today. But there is far more than enough pressure when I first turn it on, or when I turn it up.

City water or well?

Is the loss of pressure only when u have something hooked up to they faucet? Or does it happen without anything hooked up to it?

City water

Could be something in that line from re pipe

What you could do is if you have a way to run a hose from another Jose bib to that one and get a female adapter to hook back into the bib your having trouble with and shut valve off too the bin inside cut line just above it open the bin like you were going to water something then go turn on the other one and back flush it . The recipe you had done did it include pex piping or a manabloc