experienced on 2.6.0 - repro steps:

1. Download XQuartz (X client for Mac) to local Mac
2. Start Coder workspace (K8s pod), install xauth via sudo apt-get update && sudo apt-get install -y xauth
3. Authenticate to Coder via coder login
4. Run coder config-ssh to config local SSH config file
5. Run ssh -X coder.<workspace-name>
6. Run xeyes (install via sudo apt-get install -y x11-apps)
7. Observe XQuartz application opening, but no window appears