Predictive Routing 429s during JMeter load test

Need some help troubleshooting why the Predictive Routing API is returning 429 Too Many Requests when pushing 50 threads through JMeter 5.6.2. Running from Asia/Singapore on platform_api. The rate limit headers are confusing because the request count stays low but the error hits immediately. Any tips on handling concurrent call volume spikes with v2.0 endpoints?