If you run an RDS instance, I can see hitting that.
But there are alternatives like using Supabase or any of the Postgres or MySQL aligned serverless DBs like Cockroach, Planetscale, or other services if you want relational semantics and still be serverless.
On AWS, the load balancer is also surprisingly pricey; easily eats up $20/mo.
The pattern that is free on AWS and costs a fair amount on digital ocean is one or two VPS-es (or equivalent serverless/kubernetes compute) plus a managed database instance. If you don't have the managed database, the AWS free tier is a lot less attractive.
But there are alternatives like using Supabase or any of the Postgres or MySQL aligned serverless DBs like Cockroach, Planetscale, or other services if you want relational semantics and still be serverless.
On AWS, the load balancer is also surprisingly pricey; easily eats up $20/mo.