It's called a "smugshrug" or a "shruggie." Learn more about it in this extremely short 2014 article, which says:
"The emoji, of sorts, can mean anything from IDGAF to IDK or even a simple whatever."Even the first time I saw it, I could tell it combined a shrug and a crooked smile. It seemed like a no-brainer to me, something requiring little or no thought. I learned it in context, the way we learn most words. I like it. What do you think?
This photo of the emoji spelled out with French fries at Denny's is from the same little article.