Actor GetNetMode() can return the wrong value in EndPlay when the PIE world is being shut down.
Create a test actor that logs the GetNetMode() in BeginPlay and EndPlay.
Place that actor in a test map.
Launch the map in PIE with a dedicated server and one client (single process).
Stop the PIE world.
Note that the server will log NM_Standalone for the EndPlay of the actor.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-68716 in the post.