Containers unable to reach external url's because of self signed certificates

Cluster information:

Kubernetes version: 1.23.6
Cloud being used: Bare Metal
Installation method: Package Manager
Host OS: Debian 11
CNI and version: Calico 3.22.2
CRI and version: Containerd 1.4.13

I’m working on a manifest that allows me to deploy a matrix synapse server in a kubernetes cluster, but I’m running across the issue that whenever a container tries to access a url over https, the SSL certificate that gets returned is that of my pfSense box. This happens on all of my running pods, not only on my matrix deployment.

This then causes self signed certificate errors in matrix (and other applications).

After messing around in the container, I found out that whenever my containers make a dns querry, my domain gets appended to it.

So becomes

Anyone got an idea as to why this is happening?