If I navigate to any of the Spark forms (register page, billing page, etc), it will show a bunch of Vuejs syntax and errors on the screen just for a split second, before loading the proper vue. It's so fast I couldn't even tell what it was until I took a screen cast and played it frame by frame to get these screenshots from the register page as an example:
This is known as FOUC to vuejs. v-cloak will be removed by the compiler once it gets processed so you will only have the compiled content visible once it is available.