On an Intel Jasper Lake system, if ASPM L1 is enabled for Realteak r8169 device, the TX/RX speed becomes abysmal. Use the "dynamic ASPM" mechanism from vendor driver  can workaround the issue. The mechanism switches ASPM on and off based on the network traffic, so it probably mitigates the rather long ASPM L1 exit latency.
Created attachment 298663 [details]
lspci-vv from affected system (Intel Jasper Lake)
Created attachment 298665 [details]
lspci-vv from working system (AMD Renoir)