The answer to 'why is my dehumidifier blowing hot air' is that it's a normal part of the dehumidifier's operation. Dehumidifiers work by drawing in warm, humid air and passing it over a cold coil. This causes the moisture in the air to condense and be collected in a tank or drained away. As a result, the air that is blown back out of the dehumidifier will be slightly warmer than the air that was drawn in.
This hot air blowing is a sign that your dehumidifier is working properly to remove moisture from the air. However, if the air being blown out is excessively hot or if the dehumidifier is not effectively reducing the humidity in the room, there may be an issue that requires troubleshooting or professional repair.