I'm not 100% convinced that it's ear mites. Ear mites are pretty much the same across all species, and the debris that comes from ear mites is usually dark brown. Ear mites are definitely a possibility, animals get them by coming in contact with other animals that have them...could have gotten them from another rabbit, a stray cat, stray dog, etc. It could also be one of a number of other types of mites. Fortunately, ivermectin will kill most of the mites it could possibly be. It could also just be ear wax. Rabbit ear wax is dry and flaky like that and while they usually do a fair job of cleaning their ears out enough that you don't see it like that it sometimes happens that it builds up excessively. Cleaning it should be pretty easy, just use a dropper and apply some mineral oil to the ear canal. Massage it down into the ear for a minute or two, then wipe clean with a cotton ball. You can use q-tips in the folds on the part of the ear you can see, but don't stick them down in the canal itself because you could potentially damage the canal or ear drum that way. Cleaning rabbit ears can be extremely satisfying with all the huge chunks of wax that come out! I will also say that I have seen malassezia yeast infection in a rabbit ear once, although again you're looking at a dark brown, waxy discharge which it doesn't appear to be from that picture.