If the database is a shared resource across multiple teams, it makes sense that there is specific ownership of it. It could be devops, but someone needs to be looking at the larger picture. Development teams/individuals tend to be myopic when it comes to the consumption of shared resources; “my app”, “my feature”, etc.
Also, I’ve worked with some excellent DBA’s that taught me a thing or two about PG query optimization, and scaling a cluster to the needs of the business. While I’ve also dealt with some awful ones that only stood in the way of projects by creating incredibly contrived security roles. Make sure this individual is a true expert whose skills add value far surpassing that of the managed cloud services.