Usually, when someone finds a bug, the casino will give a token of gratitude regardless if the site offers a bounty for reporting a bug.

Also depends on what kind of bug you discover e.g. technical bug, glitch, unresponsive script, unpaid legit lines, etc.

To report it, obviously, you have to reach the site thru their available channels, not unless there's a specific instruction posted on the site about how to report bugs. Do you find a bug? If that can be a caused of chances of being abuse, I hope you reach the site immediately.