According to many commenters in the linked thread, it's fixed in MacOS 13.2.1. Not great that it happened at all, but good to see that it was a software issue.
But we're not being end users here, we're trying to look at what went wrong. And we don't know if the other two are true either.
It could also fall apart the day Apple decides this machine is not supported anymore, and their next OS won't have the correct drivers anymore. It's their prerogative, but will sure suck for the machine owners.
Especially when the hardware vendor doesn't provide public documentation on the correct workaround.
I did a ping test against my home router and I still get about 10% packet loss. Much better than the 40% when I first plugged it in.
PING fritz.box (192.168.1.1): 56 data bytes 64 bytes from 192.168.1.1: icmp_seq=0 ttl=64 time=11.845 ms 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=24.287 ms 64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=3.120 ms 64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=2.630 ms Request timeout for icmp_seq 4 Request timeout for icmp_seq 5 Request timeout for icmp_seq 6 64 bytes from 192.168.1.1: icmp_seq=7 ttl=64 time=0.801 ms 64 bytes from 192.168.1.1: icmp_seq=8 ttl=64 time=1.139 ms 64 bytes from 192.168.1.1: icmp_seq=9 ttl=64 time=0.772 ms Request timeout for icmp_seq 10 Request timeout for icmp_seq 11 Request timeout for icmp_seq 12 64 bytes from 192.168.1.1: icmp_seq=13 ttl=64 time=0.784 ms 64 bytes from 192.168.1.1: icmp_seq=14 ttl=64 time=0.674 ms
The above suggestion fixes it, hopefully permanently: settings->network-><ethernet interface>->details->hardware "change anything, safe and undo"