Respectfully, this isn't remotely surprising at all. If anything it's the DPP/Separtists being honest for the first time in 30 years.
The entire "Taiwanese Independence" identity was created by Lee Teng-hui, who grew up in Japanese-occupied Taiwan. As a politician he exploited anti-communist sentiments to use "China" as a proxy for criticizing Jiang Jieshi (Chang-Kai Shek).
What's especially import about Teng-hui is went to his grave an Imperial Japanese apologist. It was also under Teng-hui's leadership that Taiwan essentially weebified as a culture in the 90s. His last public interview was with a Japanese magazine claiming Taiwan's people were all ethnic Japanese.
This slipped under the radar because the KMT was the incumbent party under Ma Ying-jeou, who had abysmal approval ratings from dealing with residual 2008 Financial Crisis problems, combined with a string of party scandals under his watch.
Thing is, far as I could tell Lee Teng-hui's parents are from Fujian. He's also avoided talking about the Japanese genocide of Indigenous Taiwanese and Dutch-Formosans. Which, from my view, has some pretty clear implications for a Japanese apologies. At least Korea's Park Chung-hee had the balls to be honest about it.