There's quite a lot of breaking changes in the release notes not to mention other stuff that landed in 9.x but hasn't been backported to 8.x.
I know you said you didn't mean to be rude but this was pretty rude @RainTown. It is not obvious how to check the JDK version bundled with each version, and downloading each 300MiB+ release just to look at the JDK version is not exactly user-friendly.
You can determine the JDK version for each release by looking at the source here:
Adjust the v8.18.0 in the URL to refer to other versions as you see fit.