We have a 2020 Deere gas tractor. It has a hydraulic loader w/single acting cylinders & a trip bucket. It has power

The noise you are describing sounds like a pump cavitating. I need you to check a couple things

First, looking at the pictures below of your hydraulic tank, I need you to check the clamps and rubber hose on the suction pipe from the tank. Make sure they are tight and the the hose isn't damaged Its parts number 5,6, and 8 in the below picture.

It is also part numbers 1,2,&3 in the below picture, just to give you an idea of where they are. Also check and make sure the fitting are tight for the suction line at the pump.

After you make sure the things above are tight, I need you to check the suction filter. Its part number 44 in the below picture.

Check those things and see if that takes care of your problem. If its still doing it we will go from there.

Chad.

OK..

What was the hydraulic pressure when you checked it and how did you check it. Did you run the machine W.O.T. and stall out the hydraulics?

Did you get any fluctuation in the gauge reading at all?

That was at wide open thottle? (WOT)

Also does the noise get worse when you put a load on the transmission? Does it seem to not be as load as it warms up?

The picture below is your pressure control valve. I want you to see if the noise sounds as if it is coming from there. I use a long screw driver and put the tip to the valve and the handle to your ear. It the noise is coming from the valve, you will hear it thought the handle. It you dont hear anything there, I want you to use the screwdriver again and see if you can hear it in the hydraulic pump