One of my cats likes to lick the bathroom walls. I can't figure out what she gets from this behavior. Has anyone else experienced this?

Thank you for reaching out.
Is this a new behavior, or has your cat been licking the bathroom walls since it was young or since you moved to your current home?
Your cat may be suffering from Pica. Nutritional deficiencies can also be the cause; your veterinarian needs to rule all of these out.
Another reason is anxiety or stress, as can lack of enrichment and boredom. These can also cause your cat to lick the walls, which can be eliminated with the appropriate management.
Likewise, the texture or flavor of the paint might be attractive to her taste buds.
You can try to minimize stress, distract her and provide safe alternatives until you can schedule a vet visit. One of my clients placed catnip wall ball toys (look for organic ones), which helped minimize the licking behavior. Cat grass and cat-safe herbs may also be helpful. However, it is best to rule out any medical disorders and review her diet. Ideally, this warrants a vet health check in the first instance, especially if it’s a new behavior.
Please keep us posted once you get to the bottom of this peculiar behavior.
All the best
Melina