The phone was connected to a wfi router, presumably one connected to some magic 5G dongle compatible with the deployed 5G radios in VF's network. It's not clear whether this was open-access for VF punters, or reserved for GamerBoy in this instance.
The phone looks reasonably modern, so I would hope that 802.11ac was used, or, at the very least 802.11n, in which case the connection limit would be 1.3Gbps for ac, or 450Mbps for n (and I'd hope that the router wasn't busy at the time of the test), so the over-the-air wifi wouldn't be the bottleneck.
Saying that, initial LTE speeds were not what they currently are - carrier aggregation, MIMO and other features have injected speed boosts into the network. Also, how much bandwidth was being used for the 5G radio, too, as this isn't documented in the article - not sure spectrum is yet deployed to it's fullest extent, so it's entirely possible that different fruit are being compared in all these comments as 4G carriers are typically 20MHz per carrier nowadays, and multiple carriers are used to achieve their headline speeds.
Poorly thought out PR stunt on VF's part, though, not expecting the obvious comparisons to different fruit