Believe there is a misunderstanding here, that message is coming from your server, not our software. Therefore, something on the server is causing this message to appear. Perhaps, it is hitting some limit which is configured. Server diagnostics is outside our scope of support so your hosting provider would need to investigate why you are getting a 429 Too Many Requests message. Even if our software is the root of the issue, your hosting provider would need to provide supporting logs to detail that.
Without the 429 error gone or some logs pointing towards a software fault, we are unable to move forward in assisting you.