Is the Mixture broken?

[Buzpilot]

For all planes, the carburetors and fuel injection systems were designed to lean the mixture as the aircraft gained altitude. This is not modelled properly, hence the stumbling and backfires at higher alts.

Or it's something similar to the soundbug, were we hear wheels moving when plane is standing still or even retracted and in air.
Could it be that carburators act like plane is always bumping around on ground?
But I also suspect something wrong with oil temperature on planes without oil radiator control.
Like Hurricane oil temperature going very fast up to 90+ and staying high, even without realistic engine control.