I have to wonder what you were doing, I've been continuously hosting my own projects there for years and with the free tier they cost pennies per month to run.
You pay for the resources you use above the free tier limits. My bill for this month so far is 30 cents because I deployed frequently and my docker artifact storage size (with several years worth of deployments) dipped above the limit. Then I added a periodic job to clear out unused docker images older than one year and I'm running for free again.
