This makes it happen. It’s from here:
xpenology.com/forum/topic/60812-proxmox-repo-fix-remove-nag-and-update-to-newest-version-easy/
# Disable Commercial Repo
sed -i "s/^deb/\#deb/" /etc/apt/sources.list.d/pve-enterprise.list
apt-get update
# Add PVE Community Repo
echo "deb http://download.proxmox.com/debian/pve $(grep "VERSION=" /etc/os-release | sed -n 's/.*(\(.*\)).*/\1/p') pve-no-subscription" > /etc/apt/sources.list.d/pve-no-enterprise.list
apt-get update
# Remove nag
echo "DPkg::Post-Invoke { \"dpkg -V proxmox-widget-toolkit | grep -q '/proxmoxlib\.js$'; if [ \$? -eq 1 ]; then { echo 'Removing subscription nag from UI...'; sed -i '/data.status/{s/\!//;s/Active/NoMoreNagging/}' /usr/share/javascript/proxmox-widget-toolkit/proxmoxlib.js; }; fi\"; };" > /etc/apt/apt.conf.d/no-nag-script
apt --reinstall install proxmox-widget-toolkit
# Update proxmox pve to newest available version
apt upgrade -y