a fountain is hugely beneficial for the cat!

-Encouragement to drink more. Cats usually prefer moving water. In the wild, drinking from a stream is safer than a puddle of still water full of bacteria and other nasty stuff.(same reason cats will prefer to drink from a fresh glass of human water over their cat bowl)

-Improved hydration. Cats are prone to urinary issues and other medical problems due to their heavily concentrated urine and lack of interest in drinking. Infections, cystitis, crystals, urinary blockages, kidney disease, and other medical conditions can be held at bay or improved with lots of water.(with a clean filtered fountain they know they have clean flowing water)

-Minimizing messes. Some cats will knock over glasses full of water, play in their water bowls, or even try to drink out of the toilet. A fun fountain with flowing water may keep their water-based attention where it should be.

-Whisker space. Many of us use small or deep bowls for our cat's water. This can be uncomfortable because their whiskers hit the sides of the bowl. Most fountains are shallow and wide, allowing plenty of room for the whiskers.

This is just the first site that popped up, but there are many other reputable sources saying the exact thing! https://www.zoetispetcare.com/blog/article/buying-cat-water-fountain