She is being too aggressive, to an extent that sounds like their bond may actually be broken. Have there been environmental or scent changes recently? Did you separate them for any given time?

For their safety, I would recommend keeping them separate for now and go through some rebonding tactics so they can work this out safely and while supervised.

Bonds can also break when something is wrong with either rabbit, and considering one has scabs at this point, I recommend a vet visit for both to check for any injuries you cannot see as well as just a general exam.

I agree with Wick&Fable that the bond has been upset somehow, and that a check-over at the vet is a good idea. That level of fur-pulling is not normal in a bonded pair. When do you notice the scuffling? Is it only when they are anticipating food, or did you notice it other times as well? Did a particular behavior trigger a fight (such as a mounting attempt or an un-met grooming request)?

You should separate them if you haven’t already for now, but can keep them housed next to each other. Since you are still seeing some positive behaviors between them I don’t think it will be too difficult to re-bond them. Essentially you will let them “cool off” for a bit as neighbors, and then you will have them go on “dates” in neutral territory.

How long have they been bonded, and can you describe a bit more about their history (did you bond them yourself, how long since they’ve been spayed/neutered, etc.)?

So, bunnies don’t recognize sibling relationships and once they hit puberty they will often fight. I suspect they were never fully bonded and were more at the “tolerance” phase.

A little chasing around food is OK, but having fast chasing, grunting and pulling fur are signs that they are not bonded. Especially since Lennon will also chase if Gippy comes up behind her. Truly bonded buns have no concept of personal space and are completely relaxed around each other when they are close to each other in all types of interactions.

Unfortunately, I do think you need to fully separate, but it’s lucky you saw these signs rather than waiting until an all-out brawl, which can happen in a flash and be very dangerous for the buns. I think since you are seeing some positives still you will be able to fully bond them, but you should separate and work with them in a neutral territory.