Using a spoon, drizzle blue sour drizzle in swooping lines in the inside your glass, all the way around.
Add milk, mango syrup, vanilla syrup, dragonfruit powder, xanthan gum (or corn starch), and ice to blender and process until smooth and frothy. If you want a more vibrant pink Frappuccino, add a few drops of pink food coloring and blend to combine.
Pour the pink base slowly down the center of the glass so the blue drizzle stays on the walls of the glass.
Top the Frappuccino with whipped cream and dust half the whipped cream with a pinch of pink sanding sugar and half with blue sanding sugar. If you prefer, you can use pink pitaya powder blue spirulina instead of sanding sugars.