The joke is the dictator man looks like Winnie the Pooh (but more importantly is offended by it). The fact Winnie the Pooh is yellow is incidental but unfortunately makes the joke appetising to racists too. It doesn’t mean everyone that jokes about Xi Jinping being Winnie the Pooh means everyone is using it as a racist stand-in.
Before someone points out that it started as a racist meme - if that is true (which I have no idea), it doesn’t change much. Most people making the joke are oblivious to the racism element.
Now, it’s a perfectly valid point to make about it being a racist charicature. The trouble is most people don’t separate the nuance with “Criticise & laugh at the dictator man all you like, just please don’t propogate a racist stereotype.” and so instead it looks like they’re just defending a dictator.
And… well, I don’t really need to explain why people defending dictators are going to get ignored, do I?