Sometimes the grub config falls out of sync on OVH, because of their super weird paritioning I think.
You need to boot into rescue mode, mount the two vFAT EFI partions.
I mount mine to /media/RESCUE/efi1 and /media/RESCUE/efi2.
Compare the two (normally proxmox, although I have seen BOOT too).
Copy the newest over the oldest, very, very carefully!
If in doubt copy both to .orig files, I recommend writing down which is the latest as the copy will timestamp with todays date and time!
My scribblings normally look something like this:
EFI1 mounted from /dev/nvme0n1p1 mounted to /media/RESCUE/efi1 grubx64.efi Nov 24
EFI2 mounted from /dev/nvme1n1p1 mounted to /media/RESCUE/efi2 grubx64.efi 25 Mar 25
Then I would probably do cp grubx64.efi grubx64.efi.orig on both
Then finally
cp -b --update /media/RESCUE/efi2/grubx64.efi /media/RESCUE/efi1/
I’d probably check this a hundred times! cp should prompt if the file you are trying to overwrite is newer.