I’m currently on the legacy hobby plan. Initially, I utilized a machine with 256MB RAM and a 3GB volume, which was covered by the free allowance. Later, I switched to a machine with 133GB RAM and 16x performance for approximately one hour, which cost me around $0.07, and then I deleted it. After removing all apps except for the free builder, I set up a new machine with 256MB RAM and 3GB volume once again. However, it now appears that this usage is being billed instead of being included in the free tier.
Can you try looking at your usage page for Machines (should be on the sidebar at the left), our billing system could be slow sometimes so there’s a possibility that its just data from your deleted machine and the usage page will help you check if there’s anything running that shouldn’t be.