Here is what's up. Back in the winter of 2015 or 2016 (I forget because the years blend together now) Starbucks made a
$1 which harkened from the style of the 1960's Christmas ornaments. In the past Starbucks had made holiday cups with snowmen or other Winter themes. Super conservative Evangelicals took this ombre red cup as an 'erasing Christ from Christmas' and boycott Starbucks for maybe a month.
Years later people ravenously show up on Red Cup Day to get a free reusable cup with their order. Ironic isn't it?