For example, sudo grubby --info=ALL output:
index=0
kernel="/boot/vmlinuz-5.19.7-200.fc36.x86_64"
args="sysrq_always_enabled=1 mem_sleep_default=deep"
root="UUID=bb2bd61d-3cea-4a17-9a3a-7a2e44f66a03"
initrd="/boot/initramfs-5.19.7-200.fc36.x86_64.img"
title="Fedora Linux (5.19.7-200.fc36.x86_64) 36 (Workstation Edition)"
id="00cefb969cff4e4684ed049f476269a3-5.19.7-200.fc36.x86_64"
index=1
kernel="/boot/vmlinuz-5.19.6-200.fc36.x86_64"
args="ro rootflags=subvol=root sysrq_always_enabled=1 mem_sleep_default=deep"
root="UUID=bb2bd61d-3cea-4a17-9a3a-7a2e44f66a03"
initrd="/boot/initramfs-5.19.6-200.fc36.x86_64.img"
title="Fedora Linux (5.19.6-200.fc36.x86_64) 36 (Workstation Edition)"
id="00cefb969cff4e4684ed049f476269a3-5.19.6-200.fc36.x86_64"
sysrq_always_enabled=1 and mem_sleep_default=deep are added by me with grubby --args, but ro and rootflags=subvol=root are not. Due to the fact that my root drive is BTRFS, I think the system does not know which subvolume to mount at boot, so without the rootflags=subvol=root argument, the system won’t boot.
After every kernel update, only sysrq_always_enabled=1 and mem_sleep_default=deep (arguments that are added by me) are added to the new boot entry, however, the installation default arguments (ro and rootflags=subvol=root) are not.
After updating, I will have to run sudo grub2-mkconfig -o /etc/grub2.cfg in order to have the two missing kernel arguments added. I don’t know if this is a bug or is something I unintentionally misconfigured.