It doesn't need to be a different kind of graph, it just needs to use consistent axes. It's very weird to have the left and right labels be different when the units are the same.

It'd be one thing if it were two different quantities being measured, but we're explicitly meant to be comparing Freenode to Libera.chat, so they should really be plotted on the same axis.

Oh I see. The right axis doesn't render properly and I assumed it was just some kind of glyph: https://i.imgur.com/t4CeS1u.png

The picture look like maybe the labels on the right axis are rendered with too thick fonts so that they are unreadable.

Do you have the raw data from which the graph is produced (without JavaScripts or pictures)?

s/axe/axis/g