That is because you are using a server Xeon E5 Motherboard at a time when Teslas and Large BARs were becoming a thing whereas he is using a consumer ASUS TUF GAMING X570-PLUS with a PCIe Switch hooked in that makes the MMIO resources from a single PCIe Port suddently becoming gigantic. Unlikely to have ever been tweaked, much less tested, by vendor for that use case.