So for some reason in v2021.7.0 HomeAssistant introduced a bug that breaks a lot of systems that rely on its NGINX reverse proxy add-on to provide ssl capabilities. Thankfully the fix itself is pretty simple.
To begin, try to navigate to the site to produce the error, then in the HAS web GUI navigate to the Supervisor Logs (Settings>System>Logs)
Grab the IP that shows up in the error that reads