Without Argo, PROXY enabled and With Argo

I was just reading up on Argo and wondered, how the pathing works for proxy enabled records? The explanations I see look to only talk about not using cloudflare. See image attached. Currently I just use PROXY mode, how does that work for someone connecting from USA to UK server? Do they enter a USA pop, then go over the cloudflare backbone to a UK pop then exit to my server, or do they exit at the USA pop and transverse the wider internet?