Raised winch plate vs flat winch plate.
I had a flat RC winch plate over my stock bumper for my first winch. Worked just fine. But, when I swapped front bumpers to a Smittybilt Classic bumper, it would not sit flat. That bumper is wider up top than the stock bumper. The interference was due to the front two winch mounting bolt heads coming in contact with the bumper. I ended up drilling two large holes on top of the bumper for those bolt heads to drop into. Had I bought a raised winch plate from the get go, I would not have run into that problem.
All that went away later when I replaced it all with a winch ready stubby bumper with integrated winch mounting plate.