Systemd-boot is the boot-loader for Pop!_ OS 18.04 and above while GRUB is the boot-loader for Ubuntu and Pop!_ OS when installed in Legacy BIOS mode. ... Sometimes, GRUB or systemd-boot can break, and it may not let you boot into your computer to fix the problem.

Does UEFI use GRUB?

UEFI can handle boot selection but can't boot every OS(it can only run UEFI Applications on the ESP, e.g, grub, Linux kernel with EFI stub code, modern Microsoft bootmgr), so it runs grub.

Is Systemd-boot better than GRUB?

Conclusion: Is Grub or Systemd-boot better? If you have problems with Grub, systemd-boot provides a dramatically simplified boot infrastructure with drop-in file configuration. It's more robust, but it's also not nearly as configurable or adaptable as Grub.