uefi – Why does objcopy –dump-section modify the EFI file?

This seems very odd to me. When I use objcopy –dump-section to get the cmdline for a secure boot EFI file, the system will no longer boot. Apparently, this is because objcopy modifies the EFI file in some way. Can anyone explain why this happens?

For example:

sudo objcopy –dump-section .cmdline=cmds /boot/efi/EFI/linux.efi

Now I can examine the new file “cmds” and see the cmdline embedded in the UKI. But the next time I reboot, the system won’t accept the UKI.

Since my drive is encrypted, I have lost the entire drive and as far as I can tell there is no way to recover it. Why would objcopy modify the EFI/UKI file?

Extra credit: how can I recover my drive?