When JRE was completely discontinued as a separate offering?
First of all, the question is incorrect. JRE was not discontinued. It was only discontinued by Oracle. For example, on Linux, JRE is still available*:
$ apt-cache search openjdk-11-jre
openjdk-11-jre - OpenJDK Java runtime, using Hotspot JIT
openjdk-11-jre-headless - OpenJDK Java runtime, using Hotspot JIT (headless)
openjdk-11-jre-zero - Alternative JVM for OpenJDK, using Zero
* requires repository ppa:openjdk-r/ppa
Some other JDK providers still offer JRE as well:
- Azul Zulu offers JRE.
- AdoptOpenJDK offers JRE.
- Liberica JDK offers JRE.
Is this the case and it is not possible to download JRE directly since Java 11? Or am I mixing implementations between (Oracle and OpenJDK)?
It is correct (mostly). From Java 11 onwards, neither Oracle JDK or OpenJDK JDK has a corresponding JRE available for public downloads.
However, some other distributors of Java do provide JRE downloads (or packages) as an option. Details may be found via the "Java is still free" link below.
When JRE was completely discontinued as a separate offering?
It was discontinued for the Oracle and OpenJDK distributions with Java 11. The Java 11 release notes state:
"In this release, the JRE or Server JRE is no longer offered. Only the JDK is offered. Users can use jlink to create smaller custom runtimes."
I have not been able to find any earlier public announcements from Oracle about the discontinuance of their JRE releases. (If someone finds one, please comment ...)
Please note: this is a specific answer to the specific questions asked by the OP. For more information on the status of Java vis-a-vis licenses, distributions, vendors, support, and whether or not Java is "free", I recommend that you read the following:
- "Java is still free" written by the Java Champions community of independent Java leaders and experts.
It is a "live" document, and is likely to remain a good source of up-to-date information; i.e. more likely to be up-to-date than this Answer!