Someone has observed that Chinese cities lack population data and place=city tag may be misused, which can be the source of this problem. This is probably quite fresh thing, since we have changed the way we rank and display places in last months.
It would be great if local community could check it and fix these issues.
Maybe a solution would be to only use the city tag for places that are really a significant urban population center, and leave the counties only tagged as their boundaries in case the population of the county seat is not so large?