Lubuntu 21.10 (Impish Indri) was released October 14, 2021 and will reach End of Life on Thursday, July 14, 2022. This means that after that date there will be no further security updates or bugfixes released.
After July 14th, the only supported releases of Lubuntu will be 20.04 and 22.04. All other releases of Lubuntu will be considered unsupported, and will no longer receive any further updates from the Lubuntu team.
The supported upgrade path from Lubuntu 21.10 is via Lubuntu 22.04. You can find instructions on how to upgrade your Lubuntu installation here at our manual page.
For more information you can visit our forum post here.