Probably your video does not support the geaphic mode of installation media. How to workaround:
- Put the planned system disk into a different machine, install Proxmox there and put the disk back (network configuration has probably to be adapted afterwards)
- since throughout the versions some changes in graphic mode happened maybe an older version of Proxmox VE installation ISO works, you can upgrade afterwards to the current one.
- Install Debian 11 and Proxmox on top of it, see https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_install_proxmox_ve_on_debian