Check that the door closes properly. You can easily test this yourself by placing a flashlight in the refrigerator. If you see a light slit along the edge of the door opening, then the door must be closed properly or newly hung.
Perhaps the thermostat is set higher than necessary. Or food with a high degree of saturation has been placed in the refrigerator, forming condensation on the evaporator. We recommend thawing the refrigerator and drying it properly. Afterwards, bear in mind these possible causes.