No, those holes could not generate such temp difference. I've driven my Range Rover for long periods with various parts of internal trims removed, for various reasons, and yes I have felt cold spots, but not such a massive difference ....
Could you have some blocked ventilation tube or something and therefore "missing" that particular area?
I had years ago the opposite problem, on extreme heat on high fans with A/C on, I would get hot air under my feet, only there. The P38 Range Rover has two fans, at each end of the dashboard, and one central combined heater/AC box. I could not figure out how this was happening, as the flap motors were working properly and moreover the flap from the fan also, and the lower end had no flap of its own.
After like an entire summer of nightmare, on the next rebuild of the interior I've found the internal duct from fan to heater box had come loose, which meant air from the fan - coming from outside, before the box, was not entering the circuit, and thrown instead on the padal area..... so I had been running with half-AC 🙄