I actually suspect ambush strategy with Vance as the attack dog was discussed with Putin and had his input. This was a defeat for Trump and he holds a grudge. I wonder what was with the guy before the interview who asked Zelensky why he didn't wear a suit. Probably part of the theater.
My news never talked much about a proposed treaty. I'm guessing it involved the Ukraine giving Russia the territory it had acquired during the war and Ukraine promises the US 50% of it's mineral wealth for some sort of vague protection against further invasion. And Zelensky saying he won't seek membership in NATO. That's probably what Trump discussed with Putin beforehand and he figured he had Zelensky over a barrel and could bully him into agreement.