Look the same type that you get on PSU's for modern PCIe GPU's. They tend to just be labelled as an 8-pin 12V GPU connector (there are also 6-pin versions).
https://graphicscardhub.com/graphics-card-pcie-power-connectors/
Good picture from there:
But check those rounded corners, the top left on there is square, is the bottom right on yours is rounded, they're not exactly the same but probably named similar. Makes me think there's a specific rack PSU for that with the proper corners for it...?