That's actually a LOWER rating than Supercharger V3. Recent rating plates for the V3 cabinets show the per-stall output at 631A (greater than 615A). The voltage rating is irrelevant as the voltage is set by the car and no Tesla vehicles go above 500V.
The rating for the stall itself is just a matter of insulation strength etc. and it can easily be the case that the available voltage rating is higher than needed for the application at no extra cost (for example, if using CCS plugs off-the-shelf, they are likely to be 1000V rated for use with 800V cars, even if Tesla doesn't need that). 1000V rated supercharger stalls aren't new either - here's a rating plate from back in 2020
Ultimate/future max charge rate of V3 superchargers?
I wish Electrek would stop doing this - it's hard to spot when genuinely new info appears amid all these false "news" stories about things that aren't new.
Maybe Tesla has an intention to go above 1000V, but this doesn't really give any indication one way or the other, and isn't new given similar rated stalls have been around for years.