It has been roughly four months since ByteDance handed over TikTok’s U.S. operations to a new joint venture, but there is still not much information about what the company is actually doing to follow through with its stated mission to protect user data and prevent unwanted manipulation of its recommendation algorithm. Now, Sen. Ed Markey is looking for answers. The Democratic senator sent letters Friday to TikTok USDS, the joint venture overseeing the app’s U.S. business, and Oracle, its “trusted security partner,” calling on both companies to be more transparent about how the deal is being implemented. “Given the limited...