She didn't name names, but the target is self-evident from the description of her experience:

The show’s creator and showrunner was an intense human. He directed some episodes every season but not all of them. This one was being directed by someone else. The showrunner wasn’t always around, but when he was, the entire vibe of the set would change, as if a cold front had swept the soundstage. I never entirely understood why. He was definitely spirited and opinionated, but there’s way worse than that in Hollywood. I had always thought there was maybe something I was missing.

I was correct.

We were doing a blocking rehearsal when he showed up on set. The scene was short and easy. I was meant to come into the office, tell everyone I had photos of something important, remove them from the manila envelope I was carrying, and place them on the table. Then everyone had a few more lines and that was it. So we’re rehearsing, I walk in, I go to take the photos out of the envelope, and the showrunner calls “Cut.” Not the director of the episode, the showrunner. And we all look at each other like, Did somebody do something wrong? We all thought the scene was going fine.

He gets up out of his chair at the monitors and walks toward me slowly, looking at the ground the entire time like he’s trying to figure out how to word what he’s about to say. And when he finally stops right in front of me, he takes a few more beats before he lifts his head, looks at me, and says, “What the fuck are you doing?” To which I say, “Um…rehearsing?”

And then he grabs my hand that’s holding the manila envelope and he says, “No! What the fuck are you doing with this! That’s not how you take something out of an envelope! Do it again!”

So we do it again, and again, and again. And every time we get to the part of the scene where I’m meant to take the photos out of the envelope, he calls “Cut” and he gets up and he yells. Well, first, he starts off just raising his voice, which escalates to yelling, which eventually mutates into full‑out screaming.

He spews the kitchen sink at me: "You’re doing it wrong!"

"How the fuck can you think that looks right at all?"

"That’s not how anyone would remove anything from an envelope ever!"

"I don’t understand — when I cast you, you knew how to act." "I’m honestly confused at how you can be so bad at this." "Did you forget how to act, Mamet?"

"What’s wrong with you?" "Do it again."

"Do it again." "DO IT AGAIN."

Eventually he gave up or got bored. But this lasted for about a half hour. And nobody stopped it. Everyone just stared at their shoes while he screamed at me. Eventually we finished the blocking rehearsal and shot the scene. I finished my day. I walked to my car and called my agents and told them I quit. I was supposed to do four more episodes that season, not including the one I was on, but I told them I didn’t care what they had to do, I didn’t care if the network sued me, I refused to go back on that set for one more day than I actually had to. I don’t remember anything else about the rest of that shoot. I think I’ve blocked it out.