If the removed battlefield was applying any continuous effects, those continuous effects immediately cease, which may cause changes in the characteristics of units or hidden cards there. Example: A battlefield reads "Units here have +1 [M]." If that battlefield's owner concedes and the battlefield is removed from the game as a result, units there immediately cease to get +1 [M].
§ 652.2.c Core Rules PDF (officieel)
§ 652 If the game continues, follow these steps for Removal of a Player.
§ 652.2 Remove the Battlefield they contributed to the game if it is in use.
