1. You can make mistakes in your code.

2. Some junior developer can by mistake change the code and make it ineffective.

3. Webhook is not instant so you can get billed more than the limit.

4. There is no information which project hit the limit, so you need to Fetch all of your project ID's and then disable all of them. You need to basically disable all the projects assigned to your team/organization.

5. Vercel doesn't guarantee in any way that you won't get billed more, they are just sending an information to you (with a delay).

Hard limit should be a deal between user and company that the user won't ever get billed more than X$