Thank you!
I wrote that post from memory, so please excuse the mistake with the grub2 switch, without
that switch the correct kernel is returned as the default boot kernel.
While I could remove the Fedora 30 kernel(s), that doesn't fix the problem. As soon
as I end up with 3 bootable kernels again it always selects the wrong one!
/etc/default/grub contains:
GRUB_DEFAULT=saved
which as you say is the default for Fedora.
There's no benefit in changing /etc/default/grub as it is already set correctly.
I need to understand how Fedora/grub determines the newest kernel as that logic is somehow
broken.