The problem is when he mis-speaks in front of the world at really bad times. Nothing I have seen since the debate has convinced me that Biden doesn't have cognitive decline. I kept hoping that wasn't the case and it was just a off night.
It's probably both. There's been enough reporting post-debate that he's had "issues" going back about a year. He had a strong SOTU, so there have been some whispers that it's gotten worse in the months after that.
A little slippage is not unexpected at age 81; heck I feel like slippage began for me at about half that age. The question for voters is the degree and the velocity of cognitive decline. I have no problem with occasional gaffes and stuttering; that comes with Joe Biden. But accidentally flipping Putin/Zelensky AND Trump/Harris in the most pivotal appearance of the week is pretty bad. This isn't just "aww shucks, he made a mistake."
Not that it bears repeating, but it doesn't affect your vote or mine. But there are tens of thousands of persuadable voters across 6 battleground states, and what they ultimately decide absolutely hinges on the quality of both the candidate and their campaign. For all those who exclaim Biden has done a great job overall, I agree. But we can wish all we want that low information voters will wake up and smell the coffee, but that doesn't mean it'll happen. People have been saying since late 2023 that given a little more time, the good macroeconomic news would be appreciated by the electorate; but we're still waiting while Biden's job approval rating is stuck at 39%. Historically, that's a losing figure for reelection.