Billie Eilish is facing renewed scrutiny on social media after a clip from her 2022 interview with David Letterman resurfaced online, prompting some users to question whether the Grammy-winning singer's Tourette syndrome is genuine. The viral clip comes from Eilish's appearance on Netflix's My Next Guest Needs No Introduction with David Letterman, during which she openly discussed living with Tourette syndrome after experiencing a tic during the…