Practically everything.
I came in and decided to leave after 3 months, halfway through the trial period but I had already noticed that something wasn't working during my first week.
Starting with onboarding, which is pretty much nonexistent, after half a day of meeting with HR I met for the first time with my manager who, without even asking my name, immediately assigned me 2 Jira to work on (I didn't even have tool accesses to give you an idea, the pressure was felt right away).
When there were problems, the manager spent more time finding the guilty person rather than fixing it.
Deadlines for task deliveries are assigned totally meaninglessly, like a task that would need a week is requested for the end of the day just because that's how they promised their respective manager. They're all scared of who's higher up since firing is the norm if there's a problem.
The moment I communicated that I wanted to quit I was told, “oh I'm sorry, can you finish the task before you leave?”
I know I'll probably get one of those messages back saying they're sorry for my negative feedback, but the truth is that even the person who is writing that message knows that if they didn't pay her/him that way she/he would have already left a long time ago