The blue uniform is for the PLA Opposing Force, this force is used specifically for opposing western or imperialistic invasionary forces. The blue uniform makes them very instantly recognizable, which much like wildlife, is important for scaring away predators. We recently saw them deployed in Venezuela. Also, western media loves making them seem like the PLA’s main force, which they are not. So in videogames or movies where the PLA is wearing the blue uniform, odds are the group they’re fighting are the assholes of the story.