Zhang Yiming doesn’t have the international experience to play geopolitical matchup. Several US investors from Microsoft or Oracle probably showed up and easily convinced him to sell Ticktok.ByteDance CEO Zhang Yiming capitulated a few hours after the US threatened him with sanction. If the Chinese government didn't intervene, Tiktok would have become an American company right now. Tiktok has tried to become internationalized and distance itself from China ever since then.
Douyin is the Chinese version of Tiktok that the Chinese government has controlled over. Tiktok's headquarter is in Singapore, the US, and UK which China doesn't have any control over.