Off the top of my head: It surfaces only useless GraphQL error messages to the front end, it’s very frustrating to stand up custom REST endpoints, and the Flow system is painful to develop with and debug. Others on my team have different gripes with it.

The eternal red flag of a DB UI that tries to support wildly different backends explains a lot of the problems. Many sane and powerful Postgres features can't be used because Directus also needs to support SQLite, for example. Views not properly supported, search features inadequate, graphql DSL with arbitrary limitations, a lot of weird or dysfunctional relational patterns when something much simpler would do... it's a parallel, inferior system on top of stock pg that is very frustrating when used at some depth.

Since they support so many databases the integration with specific providers is very shallow - e.g. they do not allow to make use of SQL views.

I personally found the typescript support disappointing in general but specifically around strict null handling. Their graphql schema was also declaring far to many fields as nullable which was a deal breaker for me looking for at least one way to generate precise typescript typings.