Takei had made some inflammatory comments on why his space dock lines where it would be revealed he would be promoted Captain and commanding the Excelsior in Star Trek II were sabotaged by Shatner. He expressed this in a segment on E.T.* promoting his tell-all book "To The Stars" in which Shatner gave a lifeless performance where the director had to do continuous takes and as the takes went on Shatner delivered something which couldn't be saved. He claimed he knew what the director and the editor could do with a scene and it could not be salvaged; he thought it was a personal vendetta against him.
Here on this forum, I believe
@Maurice had a thread where he shared an audio of that scene. From my POV it seemed to me the audio showed Shatner was pretty consistent in his delivery, most has been seen in the cut of the movie, and opens the door for Takei to have his moment. Takei, as Sulu, felt flat and robotic as if he was reading the lines on set, I believe the ratios were 1:3 and all 3 takes were Shatner got better as Takei was exactly the same to me. I guess it is easy to slander a star and a living legend about a scenario when it's believed the accusation can't be disputed because the events could never be seen or heard by the public. From what I gathered were Takei's account of the events were untrue and the nature of his accusation were disingenuous.
*Entertainment Tonight.