Ubuntu LTS releases start with a kernel, then do see upgrades to newer ones from later releases via their HWE system. The 5.15 is the original “GA” one for 22.04.
On *buntu, the kernel version you start with depends on the age of the ISO image used for the install. The first two ISO releases come with the GA kernel, and the updated kernels are added later (note that here, the 5.15 is not replaced, it is still available.) Later images only include the current kernel (the 6.5), though one can manually add the GA if desired.
neon includes both the GA and the current HWE kernels, so users start out with two kernel versions ootb. This is good as a fallback. The 5.15 version is still fully supported by Ubuntu, so it sees regular updates along with the current 6.5.
On a normal boot setup, users will have the current kernel as the default boot choice, and possibly the previous version of that, as well as the 5.15. Most distros have somewhat similar schemes for this. On. *buntu, or at least deb-based systems, apt keeps up to three kernels around by default, so neon users can see 2 versions of the 6.5 and one of the 5.15 in Grub.
I will guess that rEFInd doesn’t know which kernel to make default when new versions of the older ones are installed from normal updates?
It is really easy to remove the GA kernel track if you don’t want it.
Uninstall the meta-package linux-image-generic, which will allow a run of apt autoremove to uninstall the 5.15 kernel and related packages.
This command will remove the meta-packages for the GA kernel and headers:
sudo apt remove linux-{image,headers}-generic
Then, a sudo apt autoremove will offer to remove the 5.15 stuff.
Note that this meta-package may sound serious and unsafe to remove, but it is simply a package that depends on the GA kernels and components. The important one is linux-image-generic-hwe-22.04 which is for the current HWE kernels.
sources
https://wiki.ubuntu.com/Kernel/LTSEnablementStack
https://ubuntu.com/about/release-cycle#ubuntu-kernel-release-cycle
and others
