Agree that Trump started out by keeping things fairly friendly, albeit with condescending and patronising comments such as "he got all dressed up" thrown in too.One of those times where you absolutely have to watch the full meeting and not just the highlights, otherwise you’ll be lost. Love him or hate him, Trump started the meeting by praising Ukraine. Before Zelensky turned to him, Vance started by saying Russia “destroyed” Ukraine. Zelensky decided to turn the meeting into a public spat. Maybe you think he was right to go on offense, but he was absolutely not ambushed.
However, it was Vance that escalated matters, accused Zelenskyy of not saying thank you and took it from a normal conversation to verging on shouting.
Zelenskyy then called Vance out on raising his voice, at which point Trump got involved as he knew it made Vance (US) look weak to be called out.
Perhaps Zelenskyy should have chosen his words more carefully when calling Vance out - but you can't deny it was Vance that changed the narrative here.