For anyone else labbing with Rhel 9.3 and messing with /etc/default/grub GRUB_CMDLINE_LINUX= options not taking effect, such as removing options "rhgb quiet", after running grub2-mkconfig, you now need to add --update-bls-cmdline to grub2-mkconfig or set GRUB_ENABLE_BLSCFG=true to GRUB_ENABLE_BLSCFG=false.
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html-single/9.3_release_notes/index
section 4.9 boot loader
Alternatively, we can use grubby, such as:
[root@localhost ~]# grubby --update-kernel=ALL --args="bogus_kernel_arg"
[root@localhost ~]# grubby --info /boot/vmlinuz-5.14.0-362.8.1.el9_3.x86_64
index=0
kernel="/boot/vmlinuz-5.14.0-362.8.1.el9_3.x86_64"
args="ro resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap bogus_kernel_arg"
root="/dev/mapper/rhel-root"
initrd="/boot/initramfs-5.14.0-362.8.1.el9_3.x86_64.img $tuned_initrd"
title="Red Hat Enterprise Linux (5.14.0-362.8.1.el9_3.x86_64) 9.3 (Plow)"
id="98edf952bc814fc39e39cb067e0381e8-5.14.0-362.8.1.el9_3.x86_64"
[root@localhost ~]# grubby --update-kernel=ALL --remove-args="bogus_kernel_arg" /boot/vmlinuz-5.14.0-362.8.1.el9_3.x86_64
[root@localhost ~]# grubby --info /boot/vmlinuz-5.14.0-362.8.1.el9_3.x86_64
index=0
kernel="/boot/vmlinuz-5.14.0-362.8.1.el9_3.x86_64"
args="ro resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap"
root="/dev/mapper/rhel-root"
initrd="/boot/initramfs-5.14.0-362.8.1.el9_3.x86_64.img $tuned_initrd"
title="Red Hat Enterprise Linux (5.14.0-362.8.1.el9_3.x86_64) 9.3 (Plow)"
id="98edf952bc814fc39e39cb067e0381e8-5.14.0-362.8.1.el9_3.x86_64"