That is only for bios-legacy systems. Yours is uefi.
I had typed "No. Though you can test....."
The "No." was somehow missing.
But I seriously doubt it is the 2 /boot/efi though nvme disks can be picky.
In 'normal' disks, it is a definite "No Way!!"
But if you want to try that out.
- Boot into Manjaro
- unmount /boot/efi
- Change fstab to the windows $esp
- Remount changed $esp as /boot/efi
- Do "sudo grub-install"
Do "sudo update-grub"
But warning... if you try this out, and it fails or you have done the commands wrongly, your Manjaro that you can boot now will not boot again. Think carefully. I have serious doubts it is the case. And I repeat that it will not be the case with 'normal' disks and I am unsure about nvme disk (because I do not have nmve disk) though I hear nvme can have its own 'peculiarities'.
ps: it's late here and Im logging off soon.
[EDIT] - I repeat I think it is your Windows boot that is kaput.
And it is easier to fix windows boot (though I do not know how - fixmbr, fixboot?) than to reset Manjaro's $esp partition.
ps: I have multiple $esp's in my ssd's.