There is constant confusion about this and it's caused by the fact that there are two different types of DBA: DataBase Architect and DataBase Administrator.
Many developers work with a database Architect who will design the database structures and write stored procedures. Database Administrators however often live on IT teams doing backups, knowing nothing of coding or engineering practices.
It sounds like your devs expect you to be the Architect, where you are an Administrator. I think you need to fix this expectation with them and then you won't have these problems. Also, if you are just an administrator who doesn't understand the code or engineering that went into designing the structures and writing the stored procedures, it's entirely likely the developers do not take your critiques of their work seriously. If you have suggestions or issues with the engineering work, it may be best if you can get a database Architect with more engineering know-how to champion those to the developers for you.
Also, I have to question why you are reviewing the SQL the developers write if you aren't an engineer familiar with reading complex stored procedures. It sounds like management may be trying to get their IT department to do what their engineering department does, and not understanding that they are completely different skillsets. You may wish to raise this with management.