Meaning
Two downward triangles stacked together, the double-speed version of the down button. It means going down fast, all the way to the bottom.
People use it for sharp drops, such as a price crash, plunging grades or energy fading mid-afternoon, and to send readers straight to the end of a long post: “Battery ⏬ and I still have two meetings” Some also read it as “download”. Its opposite is ⏫.