It tastes bland because the brain plays a major role in deciding how it feels along with taste buds. The gustatory cortex in brain does the main processing of taste together with tongue’s taste buds and nose’s olfactory receptors combining them to create a complete flavor profile. Food tastes bland when we have cold as our brain isn’t getting the full flavor profile.
This is the same reason some people like black coffee as their brain associates it to a good feeling whereas other find it bitter.
In short: receptor activation and different processing = different taste experience
