Can you still roll back a snapshot? If it’s the kernel parameters that are stopping you from booting you can change them from your grub menu temporarily (look here → /@/boot/vmlinuz-linuz-zen not found - #10 by filo on how to do it), i.e. they won’t be persisted across reboots but if it lets you boot into your system you can make it permanent.
Or if none of this works you can use a live usb and chroot into your system and from within chroot provide us with the update logs and the inxi to help us better understand what might be happening. To chroot you can use the command
garuda-chroot -a
from the live usb if this command fails (happens when you are using ventoy) you can follow this link to manually chroot into the system. → How to chroot Garuda Linux
Then can you provide us with the update logs? it is in /var/log/pacman.log along with the garuda-inxi. We need some idea of what might be happening in your system.
You can filter the logs to provide us with today’s logs
grep '^\[2023-10-15' /var/log/pacman.log
You can change the date accordingly.