That should have said “connected”, otherwise the modem is not in connected state.
Check the output of mmcli -b 0 to see the status reported by the bearer object.
What bothers me here is the NetworkManager output. If it was NetworkManager the one triggering the connection, it should report the connection as down, not up. There’s something wrong here.
Could also be that the connection is connected, then quickly disconnected. Would be interesting to see the MM+NM debug logs, as explained in Debugging | ModemManager