Here’s some of the backstory.
Doherty’s character was killed off in the Season 3 finale an episode that she directed.
“I just don’t feel like I have to keep telling a lie,” Doherty said.

“The narrative that I quit was assigned to me by other people.”
Combs expanded on how she thinks a lawsuit from Milano could have been justified.
There was no […] harsh words exchanged."

We do have some hints of a toxic environment from Doherty’s perspective.
It seems like a clear reference to Milano.
But Combs defended Doherty’s reputation.

“There is not a director who would not work with you again.
This time it was for McGowan and resulting from Milano.
Appalling behavior on the daily.

I cried every time we got renewed because you made that set toxic AF,” asE!reported.
However, she did say the atmosphere on set made her feel like she was back in high school.
It mentioned life lessons, including those of resilience, gratitude, and empathy.
The past is definitely over and done with."