The chart is using rough.js, which generates a random hand-drawn style every time. Currently, there is no method to lock the random seed. I'm thinking about disabling the animation to see if it can remove the jitter. It indeed seems a bit strange, haha.

The docs don't agree with you - https://github.com/rough-stuff/rough/wiki#seed - if you use a fixed non-zero value it should be the same every time.

It seems you are right, dude :)