Jose Manuel Jurado Diaz hits on an issue with row-level security:
Today, I worked on a service request that our customer reported that running a complex query this is executing in parallel but having more than 2 vCores in Azure SQL Database this query is not using parallelism.
During the troubleshooting process we suggested multiple tips and tricks, but any of them made that Azure SQL Engine uses parallelism:
Being on-premises versus in Azure turned out to be a red herring and the solution was something maybe even more difficult to spot than triggers.