Last year there were reports from people working at ESA that the situation there is very confusing, and that they're unsure if there will be an E3 after 2021 (I think), or what shape it will take. Had something to do with the companies that own ESA, but I forget the details now.
There was basically a war going on behind the scenes. One side, which included Sony, wants the show to become more fan focused and open it completely up to the public. The other side, which I'm assuming includes MS, wants it to stay as is, mainly for the press and insiders.
The issue was that E3 had become neither a trade show nor a consumer event but an amalgamation of the two. That was the problem that Layden (and I guess Sony) had with the event. Trying to focus on both the trade and fan aspects of the show was a mess for everyone involved (press have even mentioned it being far more difficult to get to appointments, demo games and do interviews then it used to be before the shift)
Layden suggested that just moving to a consumer show made more sense, because E3 is too late in many cases to work with retailers to stock product, something Sony does is February anyways.
Whether there is behind the scenes drama is something I cant verify from any source. I would assume that isnt the case because E3 has being moving to being more consumers focused. But at this point, when they finally commit, it will be too late I feel. Sony are out and I doubt they are going back if Sony's current plans work out.