Trump tried to ban TikTok, WeChat through executive action.The only thing that makes me wonder is why doesn't the US pull the trigger and already have banned TikTok completely?
People sued to stop the ban. Courts agreed and blocked the ban because of lack of evidence. It's a freedom of speech issue, you can't shutdown a social media platform on "suspicion" or "circumstantial" evidence of associate with "baddies", because you can invoke that against anyone who you disagree with, which stifles free speech.
So the courts blocked the ban. The best gov't can do is "ban government cellphones from using it". I even bet the tiktok ban on State government WiFi networks (Universities) would be challenged in court due to stifling of freedom of speech too.