I have asked the moderators of the reddit noob install to edit the post on reddit for future people that may be new to servers and arent very tech savy with servers.
https://www.reddit.com/r/homelab/comments/m7ju2e/fixing_proxmox_noob_install_tutorial/
thats because it was written wrong in the tutorial you should type this
nano /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt pcie_acs_override=downstream,multifunction nofb nomodeset video=vesafb:off video=efifb:off
I did the same as you and had to dig to find out...