Licthman's predictions are based on his analysis of what he calls "13 Keys to the White House". The "keys" include things like, the incumbent is running for re-election, the short-term economy is strong, the long-term economy has been good, there is no third-party challenger, there has been no major scandal, etc.
Tim Pool, on one of his daily evening live-streams several weeks before the election, showed that if you apply an objective analysis to Lichtman's "keys", you would conclude that Trump was going to win. Lichtman however, wasn't being objective; his analysis was applying Democrat party propaganda. So, in his analysis, the short-term economy was strong (there was no impending recession), the long-term economy was good (inflation wasn't real), there had been no White House scandal (the cover-up of Biden's health didn't happen), there was no third-party challenger (RFKJr didn't exist), etc.
It wasn't that Lichtman's "keys" didn't work any more, it's just that he refused to be objective in his analysis, and instead tried to sell the Democrat propaganda. It didn't work, and now he looks like a fool.