This is either a piece of debris, or a problem with the cartridge.
There are usually filters on the inlets to this type of valve. If you isolate the water and remove the valve from the wall then you'll see. Check that they are unobstructed and intact. If a filter is broken then something may have become lodged inside the valve.
You may also/instead see check valves, and itty bits of debris can easily get lodged on those. The noise might even be a sticking check valve.
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