Isn't GCRA a variant of leaky bucket, i.e. the token bucket described in the article?

As far as I can tell, the behavior should be the same, the difference is just implementation details and what you track.

If leaky bucket means "manages burst sizes and burst intervals" then yeah, they are similar in that regard but they do it differently. GCRA is more analogous to a traffic light where its solely time-based and there is no overhead needed to remove/add tokens so you are storing 1 less state object. For all purposes its probably a micro-optimization but being aware how GCRA works can yield less code but perhaps at the expense of obscurity of a lesser known algo.

I think you understand the differences but I think its improper to consider it a variant of leaky bucket as various resources refute