This sucks 
On a more serious note…my understanding is that F44 will ship with Kernel 6.19.10, but we are already on 6.19.13. How does that work during the upgrade?? Would this possibly mess up the Grub Menu with 3 kernels for rollback ?
If an iso installs say 6.10, and then you run an update, it will then install one more kernel, say 6.13.
It will not install 6.11 and 6.12.
It will not mess up up grub or anything else.
The iso for a clean install will install kernel 6.19.10.
If you choose to upgrade from f43 to f44 it should then pull in all the latest packages for the upgrade and no other upgrade would be required at the beginning.
If you are already on f44 then performing a dnf upgrade will simply pull in the latest packages as normal and 6.19.10 would not be an issue at all.
So i can upgrade to f44 rn? The latest version on fedora project is still 43 though.
Hmmm
OZ is just a little ahead of the UTC clock. No wonder, it is, after all, aussieland. 
You could, as long as you use dnf to do so. I am not 100% certain what time the release occurs, but I think it happens at 0000 UTC on the 28th, or right about now. My suggestion is to wait until the time in the US is the 28th, or about 5 hours from now before attempting to update.
Be aware that it may take some time for all the mirrors to be fully populated and in sync with the fedora repo.
Personally I have never tried to update early on the release date since I like to allow time for the mirrors to fully sync before I begin my upgrade to the newest release version.
I just checked the download site and it still shows 43, so has not yet been updated.
What is the terminal command to upgrade to COSMIC Atomic 44 without downloading the ISO to a USB and doing a clean install?
Maybe you can check the dedicated document
The F44 ISO has 6.19.10, but new Fedora releases have zero-day updates, i.e. on release day, new versions of some packages are made available which are ahead of the ISO versions.
If you install from the ISO, you get those the first time you do a dnf upgrade. If you upgrade from F43, you get those updated versions as part and parcel of your upgrade.
In the case of the kernel, 6.19.14 is already there for F44:
$ dnf list --available kernel --releasever=44
Updating and loading repositories:
Repositories loaded.
Available packages
kernel.x86_64 6.19.14-300.fc44 updates
I read it. When I try to rebase it gives the following error:
error: While pulling fedora/44/x86_64/cosmic: No such branch ‘fedora/44/x86_64/cosmic’ in repository summary
What am I doing wrong?
I cannot tell for sure because I don’t use atomic desktops. Maybe the mirror you are using hasn’t synchronized the reposity files for cosmic atomic 44. I would suggest opening a seperate thread and provide more information about the issue you’ve encountered.
Here is a existing thread with similar issues as yours: