To date, the debate seems to be centered around a few key areas: First, that spending over $30M in cap on 2 WR's is not sustainable and is likely/needs to be addressed this year. Second, that Higgins and Landry are seen by some as being too similar to be on the field at the same time. A third point seems to be that the Browns offense is built around the use of 2 WR sets the vast majority of the time, so a 3rd WR would have to be willing to accept minimal snaps.
Keys to this going into 2021 are that OBJ's contract is 100% guaranteed due to injury, Higgins is going to be an UFA (but it sounds like the Browns have already started negotiations). Another thing to consider is Njoku is in his final contract year and may not be sticking around, so the TE room may become less congested.
Key stats show that Landry is primarily the slot WR and his Air Yard to Target is only 8.3, while Higgins is primarily a Y (outside, off the line), with his AYtT at over 13...about the same as OBJ was when he was available. DPJ was over 16 and he plays the X.