1. visit Differentials
2. search by Responsible Users = Group, and anything else
Inspect the database queries with the DarkConsole (that can be enabled from your personal Settings > Developer Settings).
Resulting query does not contain anymore a query against differential_revision with this nonsense condition:
counterexample
r.authorPHID IN ('PHID-PROJ-plufiz5pclartkuv5ggz')
The filter still works returning the same results.