Many of Vercel's products are built on top of another service. They often charge more than using the service directly, although this has been improving recently. This site documents two of said products (KV and Postgres) and may be out of date.
Databases
Free Requests
-90%
Paid Requests
Markup: +75%
Free Storage
Paid Storage
Free Compute Time
-69%
Paid Compute Time
-2%
Free Storage
-50%
Paid Storage
Written data
Data transfer
Markup: +4%