Yes, Kasparov was wrong about being beaten by a computer, but it wasn't "AI".

• Deep Blue was brute-force search. It had no specific understanding or reasoning about chess. It was working thru 100-200 million moves per second (going several layers deep) and then scoring each decision tree by using a hand-tuned algorithm developed by Grand Masters IBM hired. If 2 (or more) decision trees scored the same it would just randomly pick one.
• It couldn't learn or adapt during the match. Kasparov exploited this by adjusting his strategy game-to-game, something Deep Blue couldn't do.
• One of its most "brilliant" moves — which psychologically rattled Kasparov — turned out to be a bug that caused it to pick a random valid move.

In the 44th move of the first game of their second match, unknown to Kasparov, a bug in Deep Blue's code led it to enter an unintentional loop, which it exited by taking a randomly selected valid move. Kasparov did not take this possibility into account, and misattributed the seemingly pointless move to "superior intelligence". Subsequently, Kasparov experienced a decline in performance in the following game....
https://en.wikipedia.org/wiki/Deep_Blue_(chess_computer)

Interestingly, modern LLMs pretty much suck at chess because there are so many permutations of moves that the LLM quickly runs out of patterns in its memory to match against and starts making dumb hallucinated moves.

Funny thing is the lessons from DB-Kasparov has basically made it into every phone, pc, etc. Your phone probably now has enough memory and cpu power to be unbeatable in most cases. Also funny is your phone will probably be able to beat "AI" (ie. LLMs) for a long time due to how differently they approach the game.