Fedora installer requires /boot to be in lower 2TB. This is not a grub2 restriction, even in BIOS mode. It's true that some old/buggy BIOSes might not support >2TB drives, so this can perhaps be justified in the case of a BIOS install (though I would prefer it to be a warning rather than an error). But it's definitely overly paranoid in the case of an EFI install, since it's safe to assume that an EFI system supports >2TB disks.
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