Ubuntu 21.04, codenamed Hirsute Hippo, was released on 22 April 2021. Ubuntu 21.04 uses the 5.11 Linux kernel, which introduces smartcard authentication and support for Intel's Software Guard Extensions and improves support for AMD CPUs and GPUs. Wayland is now used as the default on hardware, other than those that have Nvidia graphics processors. Support for drag and drop from the file manager to the desktop was also added. This release was to have used the new GNOME 40 release, but a developer decision was made to retain GNOME 3.38 instead, the same version used in Ubuntu 20.10. This decision was made to give time to address questions about the stability of the GTK4 toolkit, a major GNOME interface redesign and the unknown impact on GNOME extensions and Ubuntu's default Yaru GTK theme. In a review, Joey Sneddon of OMG Ubuntu, wrote, "Ubuntu 21.04 isn’t a game-changing release. Despite the hirsute moniker there’s little nothing hair-raising included, perhaps save for the switch to Wayland — but even that isn’t as prickly as it used to be! But it’s not a release totally devoid of value. Ubuntu 21.04 features a striking new dark theme and makes a raft of smaller UI tweaks that add up to an impressive, polished whole. There are also new installer features, a new desktop icons experience, and (of course) a new wallpaper." Dave McKay wrote in How To Geek, "the Hirsute Hippo behaved well in testing and feels like a solid, stable build. What it lacks in surface glitter it makes up for with many significant changes beneath the hood—even without GNOME 40. The 5.11 kernel, refreshed applications, and system-wide bug fixes and security enhancements are all advantageous. The change of permissions on the home directories is a welcome change, too. It’s nothing that you couldn’t do by hand in other releases, but how many actually bothered?" A review in Full Circle magazine note, "So far in this development cycle we have seen very few substantive changes. Perhaps the most important is the use of Wayland by default. Even though that is a developer accomplishment, it is pretty much 'user-transparent'. So far the next LTS release, 22.04, is shaping up to be very similar to the last LTS release, 20.04, and that is actually a good thing. In a mature distribution that already works well, like Ubuntu, wholesale changes are not needed and would cause a lot of user unhappiness. Ubuntu users today largely like how Ubuntu looks and works and don’t think much in the way of changes are needed. People who don’t like Ubuntu are probably already using something else."