Well for one example, if you select a person born on the Italian peninsula in the 1400s and they die of bubonic plague, their year of death is not correlated to years when there were large bubonic plague outbreaks on the Italian peninsula.

This is not an error I would expect a human to make if they were interested enough in demography to make a website about it. For example, the wikipedia page on this topic[1] does a reasonable job of distinguishing that plagues did not occur every year and that they varied in lethality.

https://en.wikipedia.org/wiki/Second_plague_pandemic#Italian...