“This lists being ATX 3.1 ready/compliant, but does it really include a 12V-2×6 cable and not the 12VHPWR cable, under the ATX 3.1/PCIe 5.1 spec?”

This question is for: MSI - MEG Ai1300P PCIE5 - Full Modular - 80 Plus Platinum 1300W - Japanese 105°C Capacitors - ATX 3.1 Gaming Power Supply - Black