This appears to be from this weird graph on page 137 of their S-1, "Significant increase in revenue per dollar of compute". It's not really explained well and has very not only WeWork but also Enron and even DotCom ("number of eyeballs on the page") vibes.

It _could_ be the cost of running inference to respond to requests which bring in revenue, however the cost is described as "compute and infrastructure expenses", while revenue is described as "in-period revenue". I don't see these numbers matching anything else in the filing, however I do not claim to go over the entire document.

So to be perfectly honest I'd just ignore this metric completely :)