The "extrapolated daily" seems to be a weird way of saying "on average". And I think it's reasonable enough to do, because I don't think this data exists at daily granularity, and even if it did the daily variation would not be particularly meaningful.

The chart's really only making a single point, which is that yesterday, more people in the US (probably) died of COVID than anything else. And the figures are likely to get worse before they get better.