There's no mention of the REPEATABLE READ isolation level, though it mentions that READ COMMITTED can exhibit non-repeatable read behaviour. Here's the docs:
I do believe that a developer's grasp of database concepts, like handling concurrency issues and understanding isolation levels, even if not by specific terminology, can be an indicator of their depth in problem-solving, attention to detail, and experience with complex systems.
[0] https://www.postgresql.org/docs/current/transaction-iso.html