YouTube Premiere countdown animation

YouTube has a feature called Premiere that allows creators to publish videos so that they are premiered live, at a particular time, to all viewers.

At the beginning of each premiere is a 2 minute animated countdown with bouncy music

The countdown has a flat, materialistic, modern style. However, I couldn't help but notice certain parts of the countdown that look similar to monitor calibration tools. Like the black and white stripes below the countdown that get increasingly narrower, and the colored and black and white squares at the top.

My question is, is there a known technical reason for including these certain features at the beginning of the video? Perhaps to help viewers feel comfortable with the resolution or video quality? Or is just an animation style?