shouldn't a serious heatmap (or any comparative graph for that matter) normalize the stat being displayed versus the baseline population in that bucket?

in otherwords, plot the percentage or average metric and not the absolute metric.

e.g. number of lotto winners per thousand people living in that grid, percentage of starred repos as a percentage of all repos, per capita alcohol consumption, average screen-time etc.

Edit: unless ofcourse the point of the heatmap is to show the population distribution itself. In which case the metric would be number of people per square kilometer or some such.