Pressure drops in the water supply system (well + pump “Aquarius”)

Greetings! For five years now, the centrifugal pump “Aquarius” (I don’t remember the model, power about 1 kW) has been in my well for quite a while, it was enough for everything, but at the time of shutdown the manometer showed 3.2-3.5 atm.

Recently, pressure has become lacking. Those. It gains the same 3.2-3.5 atm, then when the tap is opened, the pressure begins to drop very soon, a weak stream flows from the shower. At the same time, the pump in the well is buzzing, the motor is running, but the stream from the tap is barely possible. If you close the tap, pressure builds up again, but not as fast as before. With what it can be connected? Thanks for answers!