The vitastor-client needs a specific version of pve-qemu-kvm. When uninstalling vitastor-client, apt wants to uninstall all of proxmox. We don't want that, so we have to do some manual workarounds.
First uninstall Vitastor and cleanup
sudo apt purge vitastor lp-solve etcd pve-storage-vitastor vitastor-client-dev vitastor-fio vitastor-osd
sudo dpkg --remove --force-depends vitastor-client pve-qemu-kvm
sudo rm /etc/apt/trusted.gpg.d/vitastor.gpg /etc/apt/sources.list.d/vitastor.list
Then reinstall pve-qemu-kvm and only then cleanup all unused dependencies.
sudo apt update
sudo apt install pve-qemu-kvm
sudo apt-mark auto pve-qemu-kvm
sudo apt autoremove && sudo apt autoclean