If it is galvanic corrosion, the bronze isn’t corroding in the normal sense, like rust or acid pitting. It is more of an electrical effect. Aluminium ions flow from the bezel onto the bronze. That leaves holes in the bezel and rough deposits on the bronze. It is a natural effect when 2 different metals complete a circuit through a conducting liquid, like a battery.
The type of bronze makes a difference but only in that if it has similar ‘nobility’ to aluminium the effect will be less. Bronze ship propellors are often protected by sacrificial anodes, which will attract the metal ions coming from the hull etc. , otherwise they would end up looking like that right hand case. Sea water only makes a difference because it conducts electricity very well. The same thing can happen in fresh water.
I am reaching the limits of my chemistry A-Level + google-fu :). Someone with a bit more recent practical experience may be able to explain it better and correct any mistakes I have made. It would be good to know if Rolex did test this out and have protected the watch in some way (e.g. insulating the bezel insert). Maybe the bezel on the right hasn’t been fitted properly or there is a manufacturing fault.