Very weird. Biden has played completely into the main republican narrative. It's like he put in zero effort whatsoever to try and sound slightly energetic, almost like he went the other way. It was announced beforehand he has a cold, but still.
Any objective view would still put his performance as better than Trump's, because Trump is throwing insane lies with every other word. That's par for the course for Trump though and its already established it doesn't really effect him. Whereas all initial media reactions, even the pro-dem ones, appear to be focusing on Biden's performance.
It'll take a few days for the fact check type reporting to take prominence, but first impressions... damage done.
At least this is an unusually early debate, he can only improve in the later ones when its crunch time.