Google enabled 4K streaming on Stadia in early March, the service originally launched with a 1080p cap. Now there is a middle step - 1440p mode. If your hardware meets the requirements for 4K but your Internet can't quite handle it, then you should try 1440p. You will need a 1440p or 4K display and a Chromecast Ultra or Windows PC. There are more games coming to Stadia too - Jotun: Valhalla Edition ($15), Sundered: Eldritch Edition ($20), MK11: Aftermath ($40 for the expansion, $60 for the "Kollection") and The Crew 2: Hobbies ($50 for the base game, Hobbies is free) are all available...
Source: https://www.gsmarena.com/google_enables_1440p_mode_in_stadia_announces_new_games_and_pubg_ranked_mode-news-43458.php
