AWS S3 PUT requests get throttled

Question

I'm trying to reach the limit of 3500 PUT req/s on a prefix in AWS S3. However, I'm getting throttled too early. I'm using the Java AWS SDK.

The application made a ramp on the number of parallel requests. I noticed that if I reach a throughput of 2500 - 2600 req/s too early, after 40 seconds from the start, AWS throttles me. However, if I slow down the pace, there is no throttle.

I'm using a rate limiter (the Resilience4j rate-limiter, indeed), limiting the requests per second to 3499.

Why can't I reach the limit? Has anyone ever reached that limit? There are a lot of resources on the Internet pointing to the same page, Best practices design patterns: optimizing Amazon S3 performance, but no one is saying that that limit is effectively reachable :/

PS: No throttling on GET requests, even if I reach a throughput higher than 5500 req/s...)