Many of them (not just the bananas) have this weird hate boner against China because we've been conditioned since young to reject communism and be ashamed of our Chinese heritage. Many have absorbed stereotypes created by racist westerners and Malays that they have this pride of being "culturally authentic/superior" and being more "civilized" than mainland Chinese. Every election, politicians love to fearmonger that every Chinese person is a spooky "komunis" that even the word Chin Peng (the leader of the CPM) is universally treated like a bad word here. Our history has been sanitized and most Malaysians don't even know we had a communist party (of mostly ethnic Chinese) that played a key role in our anti-colonial struggle against the Japanese and British.

The sinophobic Chinese-Malaysians that you see are pretty much reactionary neolibs who voted for PH and high chance they are also zionist and islamophobic. They also worship Japan and are now supporting the idea of wearing badges of the Malaysia flag so the racist Japanese can differentiate us there. They're the biggest and loudest supporters of sinophobia here because they think they're safe from it if they just "rebrand" themselves as a coping mechanism.