I think you're referring to Figure ES-1 in that paper, but that's kind of a summary of different estimates.

Figure 1.1 is the chart I was referring to, which are the data points from the original sources that it uses.

Between 2010 and 2020, it shows a very slow linear growth. Yes, there is growth, but it's quite slow and mostly linear.

Then the slope increases sharply. And the estimates after that point follow the new, sharper growth.

Sorry, when I wrote my original comment I didn't have the paper in front of me, I linked it afterwards. But you can see that distinct change in rate at around 2020.

ES-1 is the most important figure, though? As you say, it is a summary, and the authors consider it their best estimate, hence they put it first, and in the executive summary.

Figure 1.1 does show a single source from 2018 (Shehabi et al) that estimates almost flat growth up to 2017, that's true, but the same graph shows other sources with overlap on the same time frame as well, and their estimates differ (though they don't span enough years to really tell one way or another).

I still wouldn't say that your assertion that data center energy use was fairly flat until 2022 is true. Even in Figure 1.2, for global data center usage, tracks more in line with the estimates in the executive summary. It just seems like the run-of-the-mill exponential increase with the same rate since at least 2014, a good amount of time before genAI was used heavily.