The scoreboard is burnt-in by the sports channel carrying the game; to the best of my knowledge, there's no way to get the raw switched video feed before the graphics crew touches it.
I understand that, but the app was from the channel broadcasting the game, so I guess they have control over it :)
They leave the scoreboard because it contains branding for the host team / stadium and frequently the local affiliate actually running the broadcast. NFL Gamepass, and both NHL and MLB live air the original broadcast feed.