I appreciate this article, maybe it is my confirmation bias but it gives real-world examples of the issues with Realtek NICs which I've always expected. I bought an MSI B550A-pro (has RTL8111H) and immediately installed an Intel PCIe NIC because I knew I didn't want to bother with any Realtek on-board. Other motherboards with both brands of 2.5GbE were also riddled with problems and like you say AMD boards with Intel GbE are rare and expensive.
I have decided to change my PC case to a Fractal Torrent Compact and now realise that I won't be able to put the Intel PCIe NIC in the bottom slot anymore because I want to have fans installed there. So I've been running for 3 weeks on the RTL8111H with the Intel card removed, just to see how it goes.
To my surprise I have not seen any issues so far. I've used my PC (Win10) for several hours at a time daily and never seen it drop. I tested it by copying a 50GB file from my NAS and it kept 930Mbps+ with ~3% CPU usage (about 6 mins).
I guess I am one of the lucky ones?? I kind of hope so because if not I will need to get a different AM4 motherboard with Intel GbE NIC, kind of like unicorns...
Many thanks again for the article!