Best practice is to put the independent variable on the x-axis and the dependent variable on the y-axis. That way you can read the graph left to right instead of bottom to top.

But yes this graph is wrong as drawn, unless it’s implying backwards time travel.

Here’s the graph with the axes (and data) flipped to match the time-on-x-axis convention. See the horizontal zig-zagging? Time doesn’t behave that way.