I’m not an expert on switching algorithms, but there are various algos they can use for dropping or rejecting packets, or QoS prioritization that are supposed to self limit even a poorly implemented network protocol and provide fair service and reasonable latency even in such a situation.

Again, a cheapo non reputable switch probably runs with whatever settings got it working the first time with no follow up testing. Networking algorithms are an area where the simple dumb thing mostly works except in edge cases and adversarial situations, and the right/proper way to do things is fiendishly complex.