UrBackup is a open source client/server backup system, that through a combination of image and file backups accomplishes both data safety and a fast restoration time.
Proxmox Backup Server is an enterprise backup solution, for backing up and restoring VMs, containers, and physical hosts. By supporting incremental, fully deduplicated backups, Proxmox Backup Server significantly reduces network load and saves valuable storage space.
Proxmox Backup Server vs Veeam Backup & Replication opinions
As of now PBS does not offer a Windows Client for Backups, so it's only "semi-okay" as a Veeam replacement (if you don't want to start SMB sharing files to other clients to then back them up...).