when does a message queue become a scaling bottleneck

hey everyone, i've been thinking about message queues lately, specifically around when they stop being a solution and start becoming the problem. we all know they're great for decoupling and async processing, but at what point does the queue itself, or the way we're using it, become the limiting factor for scaling? is it throughput, latency, ordering guarantees, or something else entirely? curious to hear your experiences and thoughts on this