When viewing my issues in Sentry, the URL given is always in port 80, but I'm using https (port 443). Why is Sentry appending the port 80?

When your app is behind a proxy/load balancer that terminates HTTPS, your actual server receives an HTTP request on port 80, while the original HTTPS connection on port 443 happened between the client and the proxy. This is why you end up seeing port 80 in Sentry.