The answer to 'why is my P-trap making gurgling noise' is that the P-trap is likely clogged or has an obstruction. The P-trap is the curved pipe under your sink that creates a water seal to prevent sewer gases from entering your home. If there is a blockage in the P-trap, it can cause gurgling noises as air and water try to flow through the obstruction.
Some common causes of a gurgling P-trap include hair, food particles, or other debris that has accumulated over time. This can create a partial blockage that allows air to bubble up through the water, causing the gurgling sound. In some cases, the P-trap may also be installed improperly or have a damaged seal, which can also lead to gurgling.