In context, I'm talking about the OpenJDK project which has no concept of LTS.
LTS is strictly a JDK vendor concept. (AdoptOpenJDK is a JDK vendor). How long a version is supported depends entirely on the vendor.
A lot of vendors have adopted the oracle LTS strategy, some offering even longer support. However, it's vendor specific.
Debian is, themselves, a JDK vendor as they are building OpenJDK themselves. So what LTS means for debian is entirely up to what Debian is willing to do to support it.
