diff --git a/doc/administration/reference_architectures/index.md b/doc/administration/reference_architectures/index.md
index f40c8fc3c67be6de2f1b541af09f8816ccd11854..a2b348fb6426228844f9a35ff1553f45f88d3431 100644
--- a/doc/administration/reference_architectures/index.md
+++ b/doc/administration/reference_architectures/index.md
@@ -332,6 +332,7 @@ Several database cloud provider services are known not to support the above or h
 
 - [Amazon Aurora](https://aws.amazon.com/rds/aurora/) is incompatible and not supported. See [14.4.0](../../update/index.md#1440) for more details.
 - [Azure Database for PostgreSQL Single Server](https://azure.microsoft.com/en-gb/products/postgresql/#overview) (Single / Flexible) is not supported for use due to notable performance / stability issues or missing functionality. See [Recommendation Notes for Azure](#recommendation-notes-for-azure) for more details.
+- Azure Database for PostgreSQL Flexible Server uses Microsoft Azure Active Directory (Azure AD) as authentication mechanism, which is incompatible with GitLab database integration.
 - [Google AlloyDB](https://cloud.google.com/alloydb) and [Amazon RDS Multi-AZ DB cluster](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/multi-az-db-clusters-concepts.html) have not been tested and are not recommended. Both solutions are specifically not expected to work with GitLab Geo.
   - [Amazon RDS Multi-AZ DB instance](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.MultiAZSingleStandby.html) is a separate product and is supported.