I like this Forbes article that explains Fox has oppo research ready to go just in case Tucker goes after them publicly. Well, it looks like they aren't waiting for that moment:
Last week, Rolling Stone reported that executives at Fox News were holding onto a dossier or so-called “oppo-file” against Carlson that they plan to use in the event he goes after the network publicly. The file in question reportedly includes complaints against Carlson’s “workplace conduct, disparaging comments about management and colleagues,” along with allegations of him enabling a “toxic work environment.” In addition to this, former Tucker Carlson producer Abby Grossberg, who has filed lawsuits against both the former host and Fox News, disclosed she has 90 recordings from her time at the network. Grossberg’s suit accuses Carlson and other senior staff at his show of creating a workplace that “subjugates women based on vile sexist stereotypes, typecasts religious minorities and belittles their traditions, and demonstrates little to no regard for those suffering from mental illness.”
Fox is feeling a ratings hit, so they're obviously trying to let their people know their firing was justified.
https://www.forbes.com/sites/siladityaray/2023/05/03/tucker-carlsons-text-on-how-white-men-fight-reportedly-prompted-fox-to-investigate-his-conduct/?sh=5a5dcf97781d