I've seen PCI devices disapperaing on reboot on other systems. Try kernel parameter reboot=pci. And by the way: r8168 can't be used for RTL8125. Realtek provides r8125 for this chip version. But this shouldn't be needed 5.9 as r8169 takes care.
RTL8125B NIC stopped working
I've seen PCI devices disapperaing on reboot on other systems. Try kernel parameter reboot=pci. And by the way: r8168 can't be used for RTL8125. Realtek provides r8125 for this chip version. But this shouldn't be needed 5.9 as r8169 takes care.