Why is my single hole kitchen faucet polished brass tarning or peeling?

Why is my single hole kitchen faucet polished brass tarning or peeling?

Over time, this clear coat can be broken or scratched with regular wear and tear, abuse or chemical attack, causing the finish to tarnish or the coating to peel. Unfortunately, it's not possible to repair the clear coat so you will need to replace any kitchen faucet parts that are tarnished or badly scratched.