If priority didn’t solve that either, I don’t know. I never use MacVLAN as I never had a separate IP address for all of my processes running on my machine. Thre are some cases when MacVLAN could be needed, but I never needed the kind of apps that could require it. In case of the bridge network, I and multiple IP addresses available on the host, I would link this topic
But I’m not sure about MacVLAN. For outgoing traffic, normally on a host machine you would configure the routing table with NetPlan or manually with “ip route” commands. But I never needed to change it in containers. If “priority” controlls which network the container is connected to first, that would be my first thought