In late March, YouTube restricted the maximum video streaming quality on mobile devices in India to 480p to reduce the strain on mobile networks and network congestion in the country. Over three months later, the company has finally restored the ability to stream full HD content on mobile devices albeit with a catch.
While YouTube users on mobile can finally stream content in 1080p resolution, they can do so only while being connected to a Wi-Fi network. On mobile networks, the maximum video streaming quality is still capped at 480p. The feature is being restored slowly so it is possible that it might not show up on your mobile phone immediately. There's no word from YouTube if it also intends to remove the streaming quality restriction on mobile data or not.
The restriction was only applicable on mobile devices as YouTube users in India were still able to stream content in Full HD or higher resolution on their PC, tablet, or Android TVs.
Netflix, Prime Video, and other streaming services had also announced a reduction in their streaming quality in late March to avoid potential network congestion as millions of people switched to working from home and there was a rise in the usage of video calls and streaming services. However, all of them had restored the streaming quality back to their original levels in June itself.