The reason he seems so incredibly weird and awkward is he can't be himself. He was himself when he said Trump was America's hitler and unfit to serve. But he wants to be POTUS so his best chance is be VP to an old man and be one heartbeat away. So he has to lie and disown who he actually is, and doing that is hard to do for most normal people so he comes off as weird.
He was light years better than Trump but he still lied over and over. Wouldn't answer who won the election, lied about a bunch of things.
One of the biggest lies of the night was the continued blame of Biden and Harris for this app they say illegal immigrants use, FYI that app was invented when.... Trump was POTUS.