Air in the line

Turn the pump breaker OFF. Shut off the water inlet valve (at the outlet of the pressure tank) and take note of the pressure on the gauge. Verify the pressure 10 minutes later. Has it dropped?

Try to gently shake the top of the pressure tank (push the top side to create a back and forth movement). Do you hear water moving? Bubbles or waves?

Open the release valve of the hot water tank to purge air. Is your problem solved?

Do you have a water treatment system?