Did you use --update-bls-cmdline with grub2-mkconfig? See 9.3 Release Notes | Red Hat Product Documentation
The grub.cfg of el9 is in /boot/grub2/ regardless of whether you boot with UEFI or legacy.
The BLS boot entries are in /boot/loader/entries/. Each entry has kernel options in it.
Without the (new) flag the grub2-mkconfig does not touch the entries.
Most kernel options are also stored in /etc/kernel/cmdline. Those are used to create BLS entry when new kernel package is installed.