There was a batch of intel onboard nic's that were (and are) problematic. Its not that well known about, and they did push a driver fix, but I dont think it totally solved the problem from what I read about it.Looking through reviews on X570 and B550 motherboards recently I did come across at least one board that had credible complaints about the 2.5GB intel nic it shipped with.
OTOH, looking for NIC cards for Opnsense everything suggests sticking with Intel for drivers as Realtek nics aren't fully supported. (Might be fixed now.... I see there's a plugin specifically for realtek which I assume resolves those issues).