If you’re using Lubuntu 21.10 (or any other Ubuntu flavor), be warned the EOL warning notice is now out.
Ubuntu announced its 21.10 (Impish Indri) release almost 9 months ago, on October 14, 2021, and its support period is now nearing its end. Ubuntu 21.10 will reach end of life on July 14, 2022.
At that time, Ubuntu Security Notices will no longer include information or updated packages for Ubuntu 21.10.
So plan your release-upgrade somewhat soon. You would have known the month, now you know the day.
Update: July 14 has been and gone, and Ubuntu 21.10 & all flavors are now EOL or end of life