Many users mistakenly believe they are watching 4K when their browser or app is actually downscaling to 1080p due to DRM (Digital Rights Management) restrictions. For example, watching Netflix 4K requires using Microsoft Edge or the official app on Windows; Chrome and Firefox are limited to 720p or 1080p.
2.1. YouTube: El gigante del contenido gratuito y de creadores paginas para ver videos en 4k