It's sad to see this downward spiral that the company is going along. As some comments mentioned, the upper management doesn't set a clear goal with expectations, and then it leads to ugly politics as if every team's goal is to look after themselves and maximize their territory. The company really has a big execution problem: it occupies a great spot in the gaming industry and then what? We got pumped up after the Pokemon Go craze, having hired a lot of people and many employees, who are also fans of Unity, having embraced the optimism as well as empowerment.
Now, there comes the reality check? BTW, the Glassdoor rating comes from 4.6 to 3.8 (as of today) in a year.
I have to say the HR plays a role here. Many other reviews said so and I think I can actually prove it from the HR response here at Glassdoor.
"...Regarding reviews, our HR team is focused on things like culture, training, and benefits, and doesn't have the time to write reviews- plus there are technology filters and algorithms the site has set up to detect fraud..." - May 31, 2018 Unity Technologies
What did I see? Dishonesty in bold capital letters. Why? You are a Unity HR employee (not Glassdoor) so how do you know "this site" has set up "technology filters and algorithms" to detect fraud? Did you actually try that (if so, it's a serious integrity issue and more) ? If not, you are just dishonest and want to respond whatever looks good to yourself to show Unity is in good shape. Also, while your HR team is so much focused, you still have time writing responses on Glassdoor (it doesn't take more time to write a 5-star all-good review, plus you can ask others to write). So, people are not stupid.
That is exactly how Unity HR handle things.