Why is ChatGPT able to beat by a 32 year old computer running a 37 year old chess program?

It said it would "definitely beat it" and that it "far surpasses the computing power and evaluation depth of an early 90s computer"

So naturally I loaded up BattleChess from 1988 and let it play

It sucked, it got destroyed, it regularly tried to make illegal moves and kept insisting it had peices where it didnt (for example telling me it had a rook at H1 when it didnt) meaning it was either cheating or kept forgetting its own moves

The laptop won fairly easily

I have no idea how any of it works but why is it that chatgpt is not better at chess?