Literally nothing.
Nor did we learn anything from Enron in 2001.
Both of those disasters were from hidden, off-balance-sheet debt that made it difficult or impossible to calculate reasonable valuations. This in turn made firms appear more-valuable than they were (thus their stock prices went up) and worse, it made insolvent ones appear to be profitable operating companies when they were not.
Its being done again because regulators of all sorts, including FASB, have refuse to stomp on this behavior.
Specifically, all the "commitments" for AI data centers and components are today not being considered debt against the firm contracting for it until the asset goes into service.
But they are debts, and there's well over a trillion dollars of them with many instances of indebtedness being more than the balance sheet debt of the company in question.
We're not talking little insignificant companies either. Oracle and Meta -- to name just two.....