Usually, an app that goes to background is disconnected from servers, and the room ownership is migrated if it is the owner.
(Behavior when going to background)
When a mobile app that uses STRIX goes to background, it is usually disconnected from the server. The time before the actual disconnection differs for the OS and its version, and if it is Android, also depends on the manufacturer or the model, but anyway it will be in a second to about 2 minutes. Under the case that there is a long delay, if the app becomes active again before the disconnection, it will escape from the disconnection and continue running.
If it goes to background and is disconnected from the server when in a room, STRIX considers it left the room. All of its replicas will be deleted from other clients when it is disconnected. The backgrounded device will handle events such as for leaving the room after returning (i.e., after becoming active).
(In case the room owner goes to background)
When a room owner goes to background, it is disconnected and considered left the room.
There is a server setting on Room Owner Migration. If it is disabled, the room is deleted as the room owner leaves the room, and other room members are kicked. If Room Owner Migration is enabled, when the room owner leaves the room, another member automatically becomes the room owner, and other members can keep playing. The client the room owner is migrated to is chosen by the room server. Please consider it is at random.