Testing repositories
The intended purpose of the testing repository is to provide a staging area for packages to be placed prior to acceptance into the main repositories. Package maintainers (and general users) can then access these testing packages to make sure that there are no problems integrating the new package. Once a package has been tested and no errors are found, the package can then be moved to the primary repositories.
Not all packages need to go through this testing process. However, all packages destined for the core repository must go to testing first. Packages that can affect many packages (such as perl or python) should be tested as well. Testing is also usually used for large collections of packages such as GNOME and KDE.
https://wiki.archlinux.org/title/Official_repositories#Testing_repositories
But why? The kernel is released as stable.
At kernel.org 5.19 is marked mainline.
It needs to be compiled, packaged and tested before the release to the core repository of Archlinux. Thatās just how it works.
You could of course do that all by yourself already if you feel like too.
I see it is in the AUR as well:
indeed 5.19 is mainline it is just released and no one want this as default , because it is not tested for enduser and not tested to work with everything depending on it ā¦ like hardware and libs and packagesā¦
The current āstable kernelā is still 5.18 till the support fades outā¦ and arch is mostly faster to switch to next stable before it fades outā¦
With the talk about old kernels are insecure it is a talk on using non supported kernels pre LTS versionsā¦ p.e.
there is one you can build if you want to use mainline:
https://aur.archlinux.org/packages/linux-mainline
Iām still waiting for Linux 6.0 
I wouldnāt mind checking that out myself. Though Iāll keep an LTS kernel installed just in case. 
I am afraid of linux-6.6.6 
Maybe thatās why Linus wants to keep it at 5.2 kernelā¦
Linux was the one talking about going to 6.x thoughā¦because x was getting too big for him in 5.x.
I miss the even/odd rhythmā¦
linux-zen version IDDQD (16696) for x128_x256
You need a battle tested kernel for security. The shiniest is also the riskiest.
The 5.19.arch1-1 kernel (and linux-zen) just landed in the Arch Testing repos today, so outside of any wild bugs/regressions, one might expect it to land in the stable repos sometime within the week if there are no problems. I think this is a crazy quick turn around, and just another reminder of why I enjoy using Arch-based distros like EndeavourOS.
On a quick side note, Arch got the latest stable nvidia 515.65.01-2 drivers on 08-03 and literally the very next day Fedora got the same drivers in their own repos on 08-04. Iād just like to give a quick shout-out to all the contributors, maintainers, and volunteers that get all these packages out to all us users at lightening speeds. A very grateful thank you to each and every one of theses contributions; all their work is very very appreciated!
Thatās a great question for the Arch Linux forum as opposed to EOS as we use their kernels and not the other way around.
You can find it here: https://bbs.archlinux.org/
Good closing words 
āclosingā