Dnf still wants to install kernel 6.3 after marking 6.2 with dnf

I used the recommended command to mark the 6.2 kernel on my system, as in link below. However, dnf still wants to install the latest kernel.

This is two different things.

1.) mark a package as “user-installed”: it won’t be removed by dnf
2.) exclude packages from being updated (dnf --excludepkgs=xxx, can also be globally defined in dnf.conf): the package xxx won’t get updated at all.

now what you want depends on your situation.
I’d recommend #1, that is the solution described in the linked post, because you don’t want to loose a working kernel on one hand but you want newer kernels to come in because you want to be able to test new kernels to see whether the bug has been fixed.