Rails 7 adds support for deferrable foreign key constraints in PostgreSQL | Saeloun Blog

In the database, the Foreign Key constraint enforces referential integrity. This ensures the parent record has to be present before creating a child record and these constraints are immediately enforced(checked after each statement). But, this behavior can be changed within a transaction by changing a constraints deferrable characteristics, which means instead of checking the constraints immediately, these checks will be deferred until the transaction is committed and PostgreSQL supports this feature in which constraints can be deferred.