Everybody knows this is a great scope for the money but as usual test equipment doesn’t use the best solutions in terms of cooling fans and associated hardware. They care mostly about keeping the unit cool and not about the noise the unit makes because usually these are used in environments where multiple equipment is run at the same time, the noise level is already high so it doesn’t matter much if a small 50mm fan is adding noise.
But it’s a totally different story for us hobbyists that are using these pieces of test equipment indoor, in our homes. We usually want units with passive cooling or with silent fans.