If you enabled ethernet tethering the Pi provides DHCP to devices via Ethernet. However the tether hides devices behind NAT so they will not be visible to other devices on the network. This is not configurable, connman provides a deliberately simple hotspot, so if you really want the devices on the Network you need to use a device that works as a bridge (not a router).
Yea. This is exactly what I'm experiencing after turning the tethering on. I guess there's no way of turning off that DHCP?