It happened randomly and completely out of the blue: one software engineer mentioned he didn't believe in the gender gap and he was promptly replied 1000 words essays by other leaders in the company shutting him down, to show that "we don't tolerate certain behaviour".
Guidelines were created to avoid future political discussions in the workplace. No-one left because of it (immediately) and we sadly didn't become famous. The engineer who brought that up quit a few months after.
After that, half of the employees hated thinking there were people thinking something different from them in the company, the other half was afraid to talk in public.
Again, I don't think there was a particular situation in the company: just a naive person who likes to talk frankly and people who get offended and are quick to attack in order to defend the "safe space" for the people who share their beliefs.