It has an old code with a collection of bad practices. Test coverage for example is less than 1%.
The code quality will change significantly depending on the department you work at, and so will the culture.
A team responsibility will change all the time and projects get canceled in mid of development without explanation. Engineers spend weeks or months on investigations that go nowhere.
Communication between teams is poor and almost inexistent between engineering departments. I know a project that was canceled after 6 months of development because managers/director didn't knew they had 2 teams in the same department working on different solutions for the same problem.
The review system became a tool for bad managers to threaten engineers and ensure they don't get negative reviews.
Many of the managers are engineers who chose an easy way to get promoted. They lack the proper skillset, many can't communicate properly, don't know how to deal with people (special with the opposite sex). This has a direct impact on the performance of everybody bellow them.
The company does nothing to solve the constant sexism in the workplace. There are people with multiple reports of sexual harassment but nothing is done about it.
Directors tell you that you should try to solve the problems or at least communicate them, but anyone who raises problems gets punished.
They try to sell the idea of a "cool startup workplace", but it's a hard corporative environment, where politics is more important than production. A place where lies and sabotage are common.