Elon Musk has repeatedly vowed to increase what he calls the “fun levels” of Twitter, a platform that is rapidly losing active users, according to industry estimates.CHANDAN KHANNA/AFP/Getty Images The CBC says Twitter chief executive Elon Musk is treating journalistic independence “as a game,” while newsrooms around the world reconsider their use of the social-media platform amid its volatile moves and declining audience. Mr. Musk has repeatedly vowed to increase what he calls the “fun levels” of Twitter, a platform that is rapidly losing active users, according to industry estimates, with competitors TikTok, YouTube, Reddit, Facebook and Instagram continuing to…