Untrustworthy managers. Anything you speak with anybody at Yelp is broadcasted to everybody else. I would advice with great emphasis: do not speak much. Do not tell your manager anything. They are creating a file against you to fire you whenever they want.
Managers at yelp have only one job: create files and micro-manage. Be very careful of old employees- they are not your friends.
The overall culture is very toxic and people rarely stick around. The ones who stay are part of this toxic culture. The HR is against you. The "policies" are just a way to fire people. Nobody follows a single workplace policy like respect, no racism, diversity etc.