The error 429 means that you have submitted too many tokens or requests in a short period of time and have exceeded the number of requests allowed.
Azure services often enforce quotas on transactions per minute (TPM). If your application or service exceeds this quota, it will start receiving 429 errors.
So you need to check your Azure portal for the specific TPM limits for your Azure AI service (in this case, Azure AI Chat Playground with GPT4o deployment and Azure AI Search). If you're hitting the TPM limits, you may need to adjust your application logic to spread out requests more evenly over time or consider increasing your TPM quota.
https://help.openai.com/en/articles/6891829-error-code-429-rate-limit-reached-for-requests
https://learn.microsoft.com/en-us/azure/ai-services/openai/quotas-limits