I don't have garlic, but mine sure love chives. Although there is stuff in allium plants it isn't really that toxic to rabbits, more toxic for parasites and said to be a preventative for coccidioses. Anyway, my rabbits eat it, and they know better than me what and how much of it they can stomach, never had any issues.
As with everything, only feed in moderation, or when they can chose themself make sure they have enough options, and had a chance to learn to listen to their instincts. Imo, they even eat some actually somewhat toxic stuff, like ivy, celandine or butterbur on purpose in small amounts as medicine.
Dogs, of course, are another matter, but they aren't the top predators to botany like rabbits. But everything that is toxic to any animal tends to end up on the internet lists. Toxiticy is also dependent on the amount, like, a rabbit would have long exploded from apple cores before it would feel any effect from cyanids.
I would be careful with exotic stuff like highly toxic decorative palnts and rabbits that aren't used to picking their greens from a wide variety.