The person posting the pic said the PC was built by a local company. Not much of a credit to their skills, apparently The PSU is also quite dusty, which makes sense given that it's the main exhaust with this airflow layout. But it also looks like the PSU fan grille is covered with ... thermal paste? It's probably just dust + a bad camera, but that stuff looks weird.
To be fair though, with that open fan slot in the front, there's plenty of room for air to flow out there and get recirculated by the front intake fan