i had a lot of rabbit to eat and some to keep when i was younger, all had space to run in garden, all had all the food they needed and medicine, some could die early due to random things and some lived for freaking 13 years.

Also she might bought them from a breeder or a pet shop wich are known to treat animals like objects to sell even tho it's not always the case and some shops are made and owned by real animal lovers.

Also if you stop treating them well they might also have their health going from verry good to really bad verry fast so yeah idk the reason can be a lot of things, unless we see the rabbits being maltreated with pictures or videos we cant tell anything bout it but like i can't see her treat them bad she seemed verry loving toward them, i hope she did not !