What’s wrong with this picture? During a fire the kitchen exhaust fan must be capable of removing flames and smoke from the building. This may result in the kitchen exhaust fan reaching temperatures that could burn anything that is combustible.
In this particular case the kitchen exhaust fan is placed on combustible wooden sleepers!
Big no no!
As per NFPA-96-14:
4.2.1. …exhaust fans… shall have a clearance of at least 457 mm (18 in.) to combustible material….