Many organizations that built applications 10-20 years ago had a very data-oriented approach to application architecture. Although mainly due to the particularities of Oracle-based systems, it became commonplace to couple the application to the database. (In the case of Oracle-connected applications, stored procedures and triggers coupled the database to the application.)
But what seemed like a good idea then causes a huge issue now when you move those applications and data to the cloud and want to leave the expensive legacy databases behind.
This architecture issue is not easy to fix after the fact. Indeed, you’ll need to do some major surgery on the application to fix the underlying coupling issue. It’s an expense that many enterprises are not willing to take on, yet it could be more expensive to continue on the current path.