I don’t think that studio interference was the problem with either BvS or SS as their plots, characters, and tone were all my main problems with those films. In fact, I would argue that studio interference is needed to save these movies. WB has a history of just giving the creatives the keys to the car and letting them do their thing. It can end well (Nolan trilogy) or it can go completely off the rails (every other DC movie ever). You then look at Marvel movies, and they are notorious for the studio interference, but they have yet to make a bad movie (I would argue that the studio interference has caused most of the films to be boring, but never actively bad).
Additional reports are that WB forced Snyder to cut his vision for Justice League from two movies to one and looking at the tonal change from BvS to JL, I would say that is likely a mandate as well, and the movie looks a lot better for it.