Possible related cases:
Unresolved 503 error issue (yesterday): https://huggingface.co/proxy/discuss.huggingface.co/t/space-stuck-on-starting-badge-despite-app-running-fine-on-port-7860/174315
Intentional blocking by HF: https://huggingface.co/proxy/discuss.huggingface.co/t/restart-error-503-factory-reset-no-rebuild-same-with-other-space/173779