Updating proxmox is super simple and easy to do. However, it's not just a simple apt-get update/upgrade for the first time. Note this should only be used in non-enterprise and non-production applications. Perfect for your homelab and free.
nano /etc/apt/sources.list
deb http://ftp.debian.org/debian bullseye main contrib
deb http://ftp.debian.org/debian bullseye-updates main contribv
deb http://download.proxmox.com/debian/pve bullseye pve-no-subscription
deb http://security.debian.org/debian-security bullseye-security main contrib
deb http://download.proxmox.com/debian/pve bullseye pve-no-subscription
nano /etc/apt/sources.list.d/pve-enterprise.list
#deb https://enterprise.proxmox.com/debian/pve bullseye pve-enterprise
apt dist-upgrade