We are building apps in Experience Builder, and when viewed in isolation, the full screen button allows these to be viewed full screen. However, when added to an ArcGIS Hub page (e.g. via an Application Card), the full screen functionality for these apps ceases to work.
This issue has been raised by other users in other threads (e.g. https://community.esri.com/t5/arcgis-hub-questions/embedded-experience-builder-app-in-hub-will-not/m...).