"Chinese roots" was a sub-heading. Did you read the paragraphs underneath? As for why it matters that the application and its employees are from China - pay closer attention to international relations between the US and China. The US banned Huawei because it was concerned about the influence of the CCP on the company and is in the process of banning an extremely popular mobile application currently (TikTok) because it has links to China. The US and China are major foes within the Pacific region: look at America's behaviour around the issues of Taiwan and AUKUS. That is the important context you seem to have overlooked here.
The most popular news application in the US having links to China is highly relevant when the two nations see each other as antagonists on the global stage, when the US has a recent history of banning popular Chinese products and services because of a purported or real link to the CCP, and when the services themselves are being used to spread misinformation and, potentially, disinformation.