Windows Dual Boot: Grub rescue issues and strangely named partitions

Hi, i have an existing windows on one of my nvme disks and i decided to try out manjaro this weekend. I had previously tried to setup ubuntu on my other nvme, and had a partition for it allready, so i wiped that in windows and proceeded to install manjaro on it with the usb.

The install went well, but my computer now boots into grub rescue prompt, saying

Error: no such device <UUID>
Error: unknown filesystem

I can boot into both windows and linux, if i go into the bios and select the respective bootloaders from there. However, even when setting the default one to manjaro, it still boots into rescue unless i click it manually in bios.

I can also see that there is another bootloader there, called ubuntu. Presumably that was not uninstalled properly.

Another interesting thing is that when running “lsblk” i can see two Windows Boot Loaders, but one of them points to manjaro.

Anyone know what could be the cause of this?

Here are some possible explanations:
https://wiki.archlinux.org/title/GRUB#error:_unknown_filesystem

What happens when you run (as root/sudo) update-grub in linux?
EFI entries can be a PITA with dual/triple booting and installing/switching OS frequently.
efibootmgr is also helpful for inspecting the boot entries.

also you should post the output here from:
cat /etc/fstab
sudo blkid
lsblk

also, since you comming from ubuntu:
is secure boot disabled in bios
is fast boot disabled in bios - you may not have this option
is fast startup disabled in windows