I've followed politics for my whole life and watched tons of Biden speeches going back decades. I was seeing his old "spark" quite a bit well into 2024. The debate, he fell off a cliff, and his follow-up interviews were even worse. 3 months before he competently delivered a barn-burning SOTU address. IIRC a few months before that, he delivered a good NATO speech. He'd slip up minor points but he also did that in 2002. Back then they used to call him a gaffe factory.