Proxmox Host Terrible Upload Network Speeds

I've had fun building a plucky little homelab on Proxmox 8.1.4 running kernel 6.5.13-1-pve. It's installed on an HP EliteDesk 800 G6 Desktop Mini PC, with the OS installed on a SATA SSD, there being a 4tb NVME btrfs pool, and there being multiple HDD's connected via USB3. Services are run an an LXC that has Docker installed, a...