Nevermind. After trying some more things for the past 20 mins, I figured out a fix.
This issue came up when I switched my hard drive from another laptop with grub installed. I just had to boot into the OS and run the grub install command as outlined in the arch linux docs: GRUB - ArchWiki
Specifically, my command was:
sudo grub-install --target=x86_64-efi --efi-directory=/boot --bootloader-id=GRUB2
I had an existing “GRUB” folder/file, so I just made a new one called “GRUB2”. After a reboot, it went straight into my OS.
I tried that out after reading this comment: