There are definitely some issues with the development and project management process but most of these issues can be overlooked and even embraced by the right developers.
The primary issue with Ubiquiti is the disdain that upper management has for its employees. Engineers, QA, business, compliance, managers, you name it. Make one mistake that management hears about and you're on the "bad employee" list. Upper management was often demeaning to employees in private meetings (at least it wasn't publicly).
Employees are seen as disposable. Entire offices have been closed in a single day. Best financial year ever? Fire 10% of the work force. Most of the employees that I spoke too were worried about their jobs even they were doing their jobs well. Morale is always low.
Employees aren't trusted to do their jobs. Upper management felt the need to micro manage most aspects of the business. If you disagree with anything you'll immediately be turned down and put on the aforementioned "bad employee" list.
If you're looking for a long-term career, look elsewhere. Even if you're looking for something short-term, I can't recommend Ubiquiti.