Yes and no. Debian's repos provide binaries for multiple version though. Since 11 has been about, Debian testing has always had OpenJDK11 and then of course binaries for newer versions. So they do ship the LTS, you just need to specify the version number, openjdk-11-jdk. They don't tag it as LTS in the package name, but someone who is using java professionally probably knows openjdk-11 is the LTS implementation.
As far as I know, Debian does not have any strict policy or dates for when they will stop building and publishing OpenJDK 11 binaries out of the jdk11u branch in the OpenJDK project.
The jdk11u branch [1] (the source code) is currently steward by Red Hat, SAP employees and other contributors, and both Red Hat and SAP have a support roadmap, which currently goes until at least 2023 (SAP) [1] and 2024 (Red Hat) [2].
So, Debian is not providing an LTS binary. Debian is producing binaries out of the source code maintained by others. Once jdk11u stops receiving updates, Debian also stops shipping updates, because Debian has no LTS commitment.
