scene/gameobject wont deactivate after trigger

Hello guys, im having trouble deactivating a gameobject/scene when my player triggers an enemy encounter. It goes into the battle scene but, you cant see it because the previous scene is still visible.

here is the code im trying to use

void OnTriggerEnter2D(Collider2D others)
     {
         if (others.gameObject.CompareTag("Player"))
         {
            deactivateScene.SetActive(false);
             SceneManager.LoadScene(8, LoadSceneMode.Additive);
         }
     }

im using additive because i dont want my previous scene get destroyed.

Imagine playing pokemon. Had an encounter, but you cant see the battle. only your player in the grass.

in addition, I would also like some help on how to reactivate said scene.

You can define a layer for invisible that main camera not render. so can set previous scene layers to it. Then you quit battle, set layer back.