Are you able to manually mount the EFI partition while chrooted? Running an update won’t fix the problem if you don’t have the EFI partition mounted properly. To that end, are you able to manually mount the EFI partition at all? That would be a very big problem if not.
While chrooted, try the following before updating:
I’m a bit confused by the partitioning scheme, as I don’t see a /boot mount, are the files usually stored in /boot stored in /efi here? Usually the EFI partition only contains EFI binaries. Unless perhaps your /dev/sda3 is a LUKS encrypted boot partition? Sorry, I’m not very familiar with Arch, it’s strange to me to not see a /boot mountpoint in the /etc/fstab
It may be a good idea to just roll back the snapshot if none of this works, though that will only change the btrfs partition, so it won’t fix any issues inside the EFI partition if there are any issues there. Here’s an article about how to do that with btrfs.