Problems running Nextcloud with Kubernetes more than one pod in replica set

I’m deploying Nextcloud 18.0.0 using Kubernetes (k3s specifically), and I find that when I set the value of replicas in the Deployment config to a value greater than 1, Nextcloud pages fail to load properly. I see a popup that says the page is not loading correctly and it refreshes the page automatically. Is this a known issue? I doubt it matters for my low-traffic personal server, but I would still like to know why this fails.