We highly encourage to use MTU 1500 for the main NIC, eth0, you can then use 9000 for the 10GbE NICs, I for example always have a gigabit NIC with MTU 1500 as eth0 and then my 10GbE LAN with MTU 9000, if you want to keep using that make sure everything in the LAN supports that and is correctly configured.
You should upgrade back to v6.10.3, delete/rename /boot/network.cfg and reboot to see if both NICs get detected.
Also switch to ipvlan (Settings -> Docker Settings -> Docker custom network type -> ipvlan (advanced view must be enabled, top right)), I see some call traces in the log related to that.
After that post new diags after you see the problem.