> On the heels of the official LiveDashboard release, Phoenix 1.5 projects now ship with LiveDashboard by default, for real-time performance monitoring and debugging tools.

and it uses uPlot [1][2] in the metrics panel :D

[1] https://news.ycombinator.com/item?id=21207132

[2] https://news.ycombinator.com/item?id=22567922