EventBridge interaction events triggering Lambda reserved concurrency limits in Spring Boot consumer

Could someone explain why my Lambda handler consistently hits the 429 Too Many Requests response when Genesys Cloud pushes interaction events through EventBridge? The official documentation reads: “EventBridge delivers events to Lambda asynchronously, respecting the function’s concurrent execution quota.” I parse the payload inside a Spring Boot @RestController bound to /api/v2/events, yet the thread pool collapses before the batch completes.

public HandlerResponse handleEvent(SQSEvent event, Context ctx) {
 event.getRecords().forEach(r -> processInteraction(r.getBody()));
 return new HandlerResponse();
}

The batch size sits at 1000 inside the bus configuration. Meanwhile, the Java SDK ApiClient throws connection timeout exceptions after roughly forty invocations. I explicitly called setMaxConnections(50) and disabled SSL validation for internal routing. Still, the concurrency ceiling refuses to budge. How must I restructure the SDK initialization or the event filtering policy to stop the runtime from throttling? My environment runs on Asia/Kolkata time, so morning shift handoffs trigger these exact spikes.