IIRC, SQLAlchemy overloads this to return an object that represents an equality check in SQL. Because it was returning an object, it was always evaluating to True, because of another of Python’s footguns: truthiness/falsiness. This was a decade ago, and these particular footguns were not even remotely the biggest culprits in our bug backlogs (another honorable mention includes accidentally calling a sync function in an async context, causing timeouts in unrelated endpoints and leading to cascading system failure).