Antigravity needs to fix there broken Quota,
Please fix it, saying generous limits and giving 4 iterations is not generous.
And counting 503 errors as iterations and not implementing a retry/backoff logic for the agent is not a good way to error handling(which by the way is the go to solution as per google in there api documentation for 503 status code errors). And not following your own guidelines is the worst way to handle this issue.
Please fix the Model Quota.