So and how we progressed a little over a month ago, Ubuntu 21.10 has been marked today as EOL, which is the same as saying that it has reached the end of its life cycle. This means that it will no longer be supported, and that they will not add new packages to their repositories. Not only will the applications not be able to be updated, but they will no longer receive security patches either, so users who remain on Impish Indri will be exposed to threats that are discovered from now on.
With already the indri in the end of its life cycle, its users have little to choose from. Unless you want to go back, which I would not recommend, the only option available is to upgrade to Jammy Jellyfish, the version of Ubuntu that arrived in mid-April 2022. It is an LTS version, which offers the possibility to stay in something endured for several years.
In Ubuntu 21.10 the jump was made to GNOME 40
Ubuntu 21.10 Impish Indri arrived on October 14, 2021, and it did so with the most outstanding novelty to use GNOME 40. The two previous versions stayed at GNOME 3.38, and to return to the usual calendar, that is, use the latest version of the desktop in the latest version of Ubuntu, in 22.04 the direct jump to GNOME 42 has been made.
The above if we stay in the main version, because Ubuntu is available in 8 official flavors, and all of them have reached the end of their life cycle. Some flavors offer 3 years of support instead of 5 in their LTS versions, but those of normal cycle, like 21.10, they are only supported for 9 months, or what is the same, the 6 until the next one and three more courtesy months to give time to update. That goes for all flavors.
Right now, Canonical is working on two fronts: in a few days they will release the ISO with Ubuntu 22.04.1, and on the other hand they are releasing images and daily updates for kinetic kudu, the October 2022 version. It will be another normal cycle, and new desktops and a kernel that will be between Linux 5.19 and 5.20 are expected.