What to do with seemingly fabricated data when researching a paper's citations
It seems like the Chart author was interpreting the Paper's research, and basically created a new chart while citing the Paper as the &quot;source&quot;, but that actual chart nor data exists on Paper at all.

Maybe the author created the chart from the paper's data and cited the paper as the data's source. You've mentioned the Chart is useful, suggesting the author added value. (Whilst also suggesting the chart is not true, which seems contradictory.)

what exactly do I do with the knowledge that the chart seems to be fabricated?

You could email the author and ask for clarification.