In most environments it is better to use latest JDK release not some old one.
LTS is associated not with version number but with vendor that provides JDK. So if you don't pay any vendor then you don't have LTS, you just have a number and hope it is in some way better thant any other number - which is not.
OpenJDK has no notion of LTS, they release new versions every 6 months, vendors decide which one of those will be supported with fixes, e.g. Azul decided that their JDK 13 and JDK 15 will be supported with fixes for longer their JDK 12 and 14.
