Biden is just old, and the cold did him no favors. He was also I think completely unprepared for the firehose of just straight up disprovable lies coming at him while also trying to actually convey his talking points. Even if well I don’t think it’s a great medium for an 81 yr old man. Listen to him elsewhere though and it’s clear he still has his marbles, unlike Trump who is on a fast decline and unable to even explain an idea. The man isn’t as young as he was clearly, and probably should have just retired long ago. But having known family and others with dementia, I don’t think Biden has dementia at all, he’s just old and debates like an 81 yr old.