nikwest Glad to hear the Ethernet port of your EX Mate Pro is now detected normally on your MacBook Pro M5 after re-plugging!
This issue was likely caused by a temporary Thunderbolt connection handshake failure between the dock and your M5 Mac, rather than a permanent incompatibility between Thunderbolt 4 and Thunderbolt 5. Re-power cycling and re-establishing the connection cleared up the abnormal recognition state.