Starting on 2021-07-01, the KDE neon Plasma LTS Edition will no longer receive updates and you must migrate to the regular user edition to receive updates. This includes security updates. Deprecating the LTS edition allows us to more efficiently use our resources for the most valuable and also most used editions of neon. This step has of course been a long time coming. We've removed its visibility from websites 3 years ago https://blog.neon.kde.org/index.php/2018/02/12/hiding-neon-lts-edition/ and the rationale for that is even more true today than it was back then.
Also see https://blog.neon.kde.org/index.php/2021/04/06/the-end-of-lts-edition/.
