Looks like you don’t understand the concept of a server, a server is not a physical representation of any device, I can make anything a server whenever I so please.
If you get crappy motherboards (server grade) or crappy servers with motherboards they can have any kind of NIC, also they can be connected directly or indirectly to your CPU using or not using PCI lanes.
Here it seemed that you made a poor decision on what you call a server, no labgore here imho.
I’ve used ASUS motherboards with both intel and Realtek NICs (for some reason dual-NIC MBs never have the same chipset)… in a number of years, tugging along in my ESXi cluster hosting 50 VMs - no issues
Realtek + ESXi are hardly existing in the same equation. One upon time but not anymore.