I also had a bad experience where I had a test website under a megabyte in a storage bucket. It was under the free tier and sat there for a few years. Then one month they sent me a bill (it was small, a handful of cents). Contact support saying that this use is under the free tier. They said that data was added then removed from the bucket. I hadn't logged into the account, no living API keys. They wouldn't forgive the charge.
Luckily my credit card had expired so they just locked my account.