If you are worried about a financial crisis caused by the Artificial Intelligence boom ending, then the key early indicator may not be slowing economic activity, but rather a series of write-downs in corporate accoutres of their capital expenditure on AI... in other words a recognition that it is not going to produce the returns expected.
When that happens, what follows will depend on how market traders ('the market') reads such write-downs.
h/t FT Lex