Boot management magic in Fedora 39

Problem: After an update to F39, a system continues to boot F38 kernels

The /bin/kernel-install generates entries in /boot/efi/loader/entries instead of /boot/loader/entries. Also, they are in BLS Type 1 format, and not in the legacy GRUB format. So I cannot copy them over.

Solution:
[root@chihiro zaitcev]# dnf install ostree
[root@chihiro zaitcev]# rm -rf /boot/efi/$(cat /etc/machine-id) /boot/efi/loader/

I've read a bunch of docs and the man page for kernel-install(8), but they are incomprehensible. Still the key insight was that all that Systemd stuff loves to autodetect by finding this directory or that.

The way to test is:
[root@chihiro zaitcev]# /bin/kernel-install -v add 6.8.5-201.fc39.x86_64 /lib/modules/6.8.5-201.fc39.x86_64/vmlin uz