Systemic issues across all departments around treatment of women and underrepresented minorities. Extreme lack of diverse representation at top levels. Employees were told that management had fixed the pay inequality in mid-2017, but no numbers were publicly released. While management is committed to fixing the issues, progress has been slow and painful.
The founding team has been slow to realize that the startup culture they once cherished has become a multinational company that is taking advantage of its most vulnerable employees (recent college grads, people who have never worked at a startup before and are fleeing large companies with bad cultures, people with non-traditional tech backgrounds, women, etc.). Meanwhile, the hired heads from the marketing and sales industries have brought their cultures of toxic infighting and office politics with them. The company's internal values sometimes feel like either lip service for recruiting or an excuse for not treating employees better.
For more perspective, look at the most recent Glassdoor reviews for Appboy (the company recently rebranded).
That being said, management truly is working to turn things around. Best of luck to them.