I made my master thesis on real-time, with a chapter where I experimented with different levels of jitter and latency. Jitter is the consistency of the latency, is it like a locked 66ms or sometimes does it go to 200ms. Jitter is more impactful than latency for a wide range of applications, from gaming to music and video call. Having a lower latency allows for lower jitter, or less jitter while keeping the same latency. Today’s discovery is huge imo.

Doesn't jitter come from the switches and routers along the path? I have a hard time seeing a fibre having significant jitter.

Also, there is a very narrow threshold of latency timings in which "real time" communication goes from looking real time to actually feeling real time. That narrow window is why people end up interrupting each other or feeling like they can't get a word in edge wise on video calls all the time.