Consider if a guy in Shanghai who is a big fan of James Harden. Is invited to an American Halloween party. He decides he wants to be his favorite NBA player and wears a Harden jersey, get's a big fake beard and paints his face black. Many Americans are going to be offended by a Chinese guy putting on blackface while he might rightfully mystified why they are since he's just pretending to be his favorite player and in his mind is paying tribute to James Harden down to trying to match his skin color. The point is someone in China isn't going to know about the legacy of blackface and things like Minstrel shows. In the same way I don't think most Americans understand how much things like the Opium War and the carving up of China by foreign powers matters to the Chinese.
Extraditing ethnically chinese HK citizens to shadowy mainland dungeons has about as much relationship to the opium war as dinosaurs do for causing global warming by dying and turning into fossil fuels. It's basically the MS-13 level of argument here. Yes, I get mainland Chinese are very sensitive about colonial legacies. Unfortunately they disingenuously use this as cover to rebut criticism of atrocities like in Xinjiang. It's not really the same as African American legacy of slavery because for the most part, African Americans are still systematically oppressed, while China is now a super powerful giant country.