Werner competing for the No.10 role? If the 4-2-3-1 would cause problems because Mount and Havertz would be competing for the No.10 role (Havertz has the higher ceiling compared to Mount in terms of creativity and goal threat to shine in the No.10 role), then equally, the 4-3-3 is already causing problems because of how Werner is being used and I have major doubt whether Lampard even sees Werner as the main ST in the long run in this 4-3-3.
If we are to play Werner as the main striker, then 4-2-3-1 could be a possibility to do so. Unlike 4-3-3 where he might get isolated upfront (would still like to see it tried at some point), he would have a No.10 closer to support him in addition to the 2 wingers. At the moment, I'm not sure if 4-3-3 will be main formation going forward especially when Lampard just stumbled upon it.