Can you confirm that you’re running 6.6.6 or later? uname -r
Because F39 seems to have an (installation-time?) bug whereby the configuration is not bootstrapped to turn on “when installing kernel version make it the default”
See thread right about here:
If you’re hitting that issue, after fixing/creating the config file referenced there, you can either reinstall 6.6.6
sudo dnf reinstall kernel{,-core,-modules,-modules-core,-modules-extra}-6.6.6
or go for 6.6.7 which is already looking good in updates-testing
sudo dnf --enablerepo updates-testing --refresh --setopt=fastestmirror=true up 'kernel*'
To trigger the make-default logic.