According to the IEP, the golden rule:
The most familiar version of the Golden Rule says, “Do unto others as you would have them do unto you.” Moral philosophy has barely taken notice of the golden rule in its own terms despite the rule’s prominence in commonsense ethics.
This rule has a simple structure and akin to mathematical axiom in its simplicity. This, at least to me, remind me of another simple ethical axiom:
Act only according to that maxim whereby you can, at the same time, will that it should become a universal law
From Kants perspective, what are the limitations of the golden rule? If as a rule it cannot work, it can only be that it can't be universalisable.