The props are damaged, either chipped or not securely fastened

Bad motor

The motor or ESC is overheating

Ensure your props are in good condition. Chipped or loose props will force the motors to work harder to lift the same weight. If your props are loose, it's usually due to worn prop gaskets, which should be replaced

When the drone is powered off and on the ground, manually spin the motor. While it's normal to feel the ball bearings, there shouldn't be any spots that are difficult to turn or any unusual noise

Allow the drone to cool down in the shade, or cool off the motors and ESCs with water