The spots on the sheet rock, next to the smoke detector, is mold. Some molds can start to grow within 24 hours of moisture being present. Other types, of mold need 7-10 days before they really take off. When we see this amount of color on the walls and ceiling’s, there’s certainly a need for microbial remediation.
The reason there is different colors on the sheet rock is due to water. When water presents it’s self , on most construction materials, it leaves a residue or water mark as it dry’s. This is one way of being able to identify potential problems, or previous water issues when looking to figure out what is going on.