Their most most recent update replaces all this with a list of recently updated PRs and issues. I've been learning on it heavily since it came out. One of the few recent changes that really feels like a clear improvement.

Haven't used the dashboard in years. What's on it now might be more useful. The homepage for me should be set to Notifications.

At any rate, the feed is still available and you can reach it via browser autocomplete. I open GitHub by typing "not" in my URL bar and landing on the notifications page.