The warning button is basically nothing more than a thumbs down feature, the issue with it is that a) it's anonymous b) it can be used by any mentor for any reason they feel like c) it's called "A Warning!" and d) Nobody else can see it except the person who gets it, which encourages bullying behavior.
This means one person that obtained mentor and hates people or just enjoys trolling can give people warnings for any reason they want, and due to the nature of the wording they can think it's far more serious than it actually is and that they did something wrong.
A new player asking for help and getting a warning is not going to use this feature again, and is going to be pretty mortified. Not knowing it was some mouth breather that did it for fun.
This feature is custom made for a handful of people to discourage use of this chat system over time and bully users who are using it properly.
I would suggest:
Either remove the warning system (why is it even necessary when you have the silence option) or make them viewable by all when someone gives one out (or at least all mentors so we know if someone is abusing it and know who is doing it).
The main argument for its removable is, why is there no downvote system on this forum? Because it would be abused, it's the same in the game. People are abusing it.