Getting Application failed to response even though the service is running.

The proper logs are in the Deploy Logs as well. The server is running fine. However calling the generated domain returns

{
    "status": "error",
    "code": 502,
    "message": "Application failed to respond",
    "request_id": "mPhJzR3OQn-aUAt63Jlftw_1243561751"
}

for all endpoints

NestJs
fastify.