When using an existing connection for de SchemaValidator (org.hibernate.tool.schema.spi.AbstractSchemaValidator), the JDBC connection is wrapped in a JdbcConnectionAccessProvidedConnectionImpl. This sets autoCommit to true.

There is no code path to call JdbcConnectionAccessProvidedConnectionImpl.release(), which would reset the autocommit mode. I suppose it is missing from ImprovedExtractionContextImpl.cleanup(), as it is present in ExtractionContextImpl.cleanup() but that seems unused.