Since the HMD Global online unlock server is down, you cannot request a code via email easily. You must extract the code from the phone's partition.

edl tool or ADB (if the device allows getvar).

: The device will display a warning message upon every boot indicating the software integrity cannot be guaranteed.

Nokia Tips & Tricks | Improve Speed, Customization, and Camera! 25 Jun 2022 —

To truly unlock bootloader better on your Nokia 34: