Its simple. Humans are addicted to blame thinking. People instinctively expect a just world, where bad things are a consequence of some form of sin from bad people and good things are a consequence of some virtue from good people and all problems are some sinners fault. A large fraction of people can't comprehend a world where bad things happen to them and nothing/no one is to blame. In the absence of reason they invent one. My kid got autism? I bet it was the vaccine shots. School shooting? I bet it was those violent video games. Internet connection went down? I bet it was because I just tried to scan a document (yes this is a real example). Any explanation, no matter how spurious, is more palpable to the human mind than "this is random and out of our control".

Throw some confirmation bias on top of it. The easiest group to blame for bad things is the group you already disliked. Traditionally this means foreigners, other races, and heretics. Blaming China both let's people have their imagined just world and vindicates whatever pre-existing hard-line stance they had on China. It's no secret that a lot of people already had a hard-lie stance on China for unrelated reasons (Eg the trade war).

In conclusion the human logical apparatus is bugged, no one is releasing any patches, and the whole issue is emotional because who you blame is tribal signaling dressed up as rational interest.