DIAGNOSIS The Midea Cube uses a turbo-style fan to move a lot of air, and on its highest speed (which is often the default when you first turn it on), it can be surprisingly loud. It's probably not broken, just running at max.
FIX Try lowering the fan speed. Press the "Fan Speed" button on the control panel to cycle through the settings—it should go from High to Medium to Low. Low speed is significantly quieter and is often sufficient for maintaining a humidity level unless you're in a very damp, large space. Also, make sure it's not right up against a wall or curtains, as that can cause turbulent noise.
IF THAT DIDN'T WORK If the noise is a grinding, rattling, or buzzing sound rather than a smooth whoosh, the fan might be hitting something or its bearings are faulty. Unplug the unit, remove the side panel and filter, and look inside with a flashlight. See if any debris (like a loose piece of foam or a bug) is near the fan wheel. If you see something, you can carefully remove it with long tweezers.
HEADS UP Dehumidifier noise is very subjective. In a quiet bedroom, even Low speed might be noticeable. Placing it on a thick rubber mat or carpet pad can dampen some of the vibrational noise traveling through the floor.