Apple has returned to advertising at its normal level on Twitter, according to Elon Musk, who also confirmed Apple is Twitter's biggest ad client. On November 28, Twitter CEO Elon Musk engaged in a tweet-storm against Apple, including claims Apple had "mostly stopped advertising on Twitter." One week later, and Musk has changed his tune. During a Twitter Spaces conversation caught by Bloomberg on Saturday, Musk said Apple has "fully resumed advertising on Twitter." Musk didn't say how much the advertising spend was for Apple, and didn't go much further on the topic, other than to say that Apple was...