I am running into the same error message and issue. I have also someone on reddit that is trying to do the same thing. None of us seem to be able to make this work.
I want a compose stack to create a few DB/backend related containers, and only ONE container have a connection to a IPVLAN L3 network and that same backend network (Total two networks)
I am creating external networks. I have tried one ipvlan and one bridge, and have tried using both networks as ipvlans nothing seems to work.
I have found that if I use lists instead of a mapping (with a defined IP) I do get the stack working, but networking assigns all of the containers to both networks… Even though the only one container has both networks defined.