Alright, I've seen this kind of thing a lot for many places and the way it is often framed is sort of inaccurate.
A lot of professional cameras deliver a very, very flat image that just looks like bleh. Here's a sample: https://youtu.be/ND72L26Tm9w
The idea is that this kind of really flat footage preserves the raw data captured by the camera before the camera does any kind of processing to it, so that you can do the color processing in post, better than the camera can (or worse, if you don't know what you are doing).
Chances are this footage was originally very, very flat, similar to the vid I linked to initially, then two different people color graded it. It is kind of impossible to tell which was more faithful to reality, and neither is really the "original". It's not like slapping a filter onto something, both have some kind of "filter".
Looking at the vid, it looks like the English language BBC version is the one CLOSEST to the original footage (it actually looks a lot like the flat footage some cameras will give you before you color correct it, it looks kinda like they didn't do any grading, that is also possible), BUT closer to the original footage does NOT mean closer to reality, because, as you can see, the footage straight out of the camera looks disgusting, murky and desaturated. So it's not a case of adding a filter on top of it, it is a case of not using enough "filter", or not using an accurate "filter".
My theory: BBC China sent edited footage before they color graded it to English language BBC, because idk, time constraints or something? So they were like "eh whatever we'll just subtitle this and put it online". Meanwhile BBC China actually went through the trouble to color grade it and make it look like, you know, real stuff and not gross mush.
Perhaps it was intentional, or it was a case of the BBC being like "hurry up, we translate this shit too and there is a deadline" so they were sent the ungraded footage and then they didn't bother to grade it to meet some kind of deadline (it did come out 1 day before the Chinese version). Maybe they didn't even figure out they had to grade it.
Yes, I've done some of that in the past too and I also think they shot in log or something and didn't grade it or at least barely graded it.
bottom one also looks like its got the saturation and contrast jacked up
My immediate thought is BBC would want to make the sky look greyer to make it look like the PRC isn't getting their chronic air pollution problem under control by now.
