Since Covid, the South Korean hate for China just skyrocketed. Many willingly fell for the US propaganda and blamed the Chinese for Covid. But for me, the root cause for that hate, I believe is an identity crisis. Many South Koreans for decade have enjoyed being the #2 most advanced East Asian, behind the Japanese. During those years, their true rival was Japan, hence they hate Japan intensely then. The Chinese at that time were regarded as lower-class East Asians whose purpose is to serve the more advanced South Koreans. Low threat, but also not to be respected. Kinda like a South Korean version of caste-based racism. I've read this kind of view from a number of Korean opinion pieces, and social media.
Many South Koreans worship the Americans like god. They aspire to be at the same level as the Americans, thereby becoming more 'advanced' than the other East Asians. They have shamelessly culturally appropriated many of American culture like music, films, Halloween, food, and Christianity. They shamelessly adopt the American Corndog, while raging at the Chinese for rightfully classifying Kimchi as a version of pao cai. They shamelessly copy American fashion, while hating the Chinese for appreciating the hanbok worn by the Chinese Koreans. In the last 5 years, I have seen South Korean films bashing China much more than Japan. That means that they have have already shifted their hate from Japan onto China.
The South Koreans now view the Chinese as an existential threat, because of their identity crisis. The Chinese have much greater history than Korea. While a big part of Korean history was becoming a vassal state of China, and a colony of Japan. The 21st century was supposed to be South Korea's chance to forge their own glorious history. But they mistakenly thought that they can forge a glorious history by becoming a vassal and facsimile of the Americans. Nevertheless the Chinese have caught up fast, and are now practically on par with them. The Chinese are also challenging the hegemony of Americans, their patron. This shocks and infuriates the South Koreans, as their position as the 'greatest of the East Asians' is now under threat by the very people they thought, whose era is over.
I think that by doubling down on America, and hating the Chinese, the South Koreans are dooming themselves. They are blinded by superiority complex and are following a dying Superpower. In time, they'll be left behind by the Chinese. I dislike SK, but in the meantime, they are still a very competent nation. Their industries are very competitive, their shipbuilding is still world leading, and their defense industry is quite formidable. My only concern now is that South Korea might be heading on a path to fascism. Could the hate reach to a boiling point, that South Korea finally abandons its 'neutral position' against China and starts to threaten China directly? Not likely, but not impossible also, as the Yoon government is still evolving, and has many years to go on too.
Nevertheless, we must not turn to hating the Koreans as a whole. The North Koreans are friendly to the Chinese, and the Korean Chinese are proud citizens of the PRC. They have not been corrupted by Western racist culture. Plus, there are still a number of decent South Koreans living in China. It is unfortunate that their home country have become like that.
P.S.: I have not actively boycotted South Korean products. But I have stopped buying Samsung, and many other high profile brands. They seemed quite arrogant for me. I have also mostly stopped watching Korean films. They are no longer as entertaining anymore. Nowadays, they feel too 'American'. I don't listen to any K-pop rubbish, but I used to observe millennials going crazy about K-pop. Nowadays though, they have grown bored of K-pop and have moved on to Japanese Anime and Chinese pop culture. How funny.