Surely it happened. YouTube got support for HDR video for iPhone X.
High Dynamic Range Imaging (HDR) – technology for working with images and video, the brightness range of which exceeds the capabilities of standard technologies. Such images look much brighter and more saturated than normal images.
It looks like this:
To change the quality, click on the symbol of three vertical dots -> Quality . If the video is available HDR, it will be written directly in front of the video resolution.
To fully appreciate the advantages of technology, you need to set the screen brightness to 100%.
HDR is available on the iPad Pro 10.5 “, 12.9”, iPhone 8, 8 Plus and iPhone X, but only the latter has received technology support on YouTube.