The last several days have given anyone who might have already had qualms about TikTok even more of a reason to be suspicious of the popular video-sharing app owned by Chinese parent company ByteDance. After telling me in an interview back in August that he suspected a regulatory shoe of some sort would drop soon, for example, FCC Commissioner Brendan Carr took his strongest stance yet against the app this week. Specifically, he says that because the app is now so pervasive — more than 200 million downloads in the US — and because there’s also such an acute overhang...