In the late 2010s, Jon Castelli’s profile grew in the production world with world-class session work for pop royalty. Since forming his engineering team The Gift Shop in 2016, he has burnished the smooth pop-rock of Harry Styles, provided future R&B jams by Khalid and 6LACK with a lush veneer, and demonstrated his ability with a boot-rattling low end on collaborations with Nicki Minaj and Lil Nas X.