How to Fix Can’t resize Kali Linux & Parrot OS VM screen/display via virt-viewer running on Proxmox VE (PVE) (With default xfce4 Desktop Environment)
So I don't have to keep looking for this blog post when I create a VM that has this issue.
Credit to DannyDa at https://dannyda.com/2020/10/22/how-to-fix-cant-resize-kali-linux-vm-screen-display-via-virt-viewer-running-on-proxmox-ve-pve-with-default-xfce4-desktop-environment/