At first I wanted to deposit the 50 USD that they ask me for in the verification but after what I mentioned above I am not sure about making that deposit.
By asking here first before doing any action, you just saved yourself $50. This is an old scheme; they made you win with your bonus, then they ask you to verify your account by depositing first before you can withdraw your winning. Casinos that do this scheme are new casinos; you cannot find this rule on established casinos.
I first encountered this scheme four years ago, and yet the scheme still persists, even though there's a lot of article writeups and forum discussions about this scheme.