Basic SQL yeah, probably. Actually knowing SQL and how to write good SQL and understanding the tradeoffs between different query plans (and the tradeoffs between different schemas). That's rare.

And yeah, obviously, there will be bugs in your SQL. And writing good tests for the database layer is always tricky because there's usually some pushback to setting up a database on the CI instance, and so on. It's not simple, but ignoring it by using an ORM doesn't make it simpler, it just means you have less options when it goes wrong.