In an Instagram video posted on April 1, lifestyle influencer Melissa Strahle poses outdoors before an American flag as soft instrumental music plays. “AI lets me focus on what matters most,” she tells her 1.4 million followers. “We need to invest in American-made AI to ensure America leads the way in innovation and job creation.”Strahle labeled the post an advertisement, but she didn’t disclose what organization had paid for it. It turns out the funding came from Build American AI, a dark-money...