Hi, this isn't a bug - at least not on the RN side. You haven't said what engine you used here, however, I'm more than sure it is Octane as only in Octane I found Depth of Field turned on by default. Try to change that in Octane - turn off DOF or set Exposure on camera to 0 (? I guess so ?).
If you want to report a bug, make sure you can recreate it, and please make yourself familiar with How-To: Bug Report - The bug report template should auto load when you select the appropriate tag when creating a post 🙂 Plus, if it relates to the rendered image marking engine will never hurt 🙂