IFAB Laws of the Game - Law 11: Offside - 2. Offside offence states that:
A player in an offside position at the moment the ball is played or
touched by a team-mate is only penalised on becoming involved in
active play by:
- interfering with an opponent by:
- preventing an opponent from playing or being able to play the ball by clearly obstructing the opponent’s line of vision or
If we assume that German #11 Timo Werner is in clear offside position (which is not the case) and given that he is positioned right in front of the Norwegian goalkeeper obstructing his line of vision, then it means that he causes an offside offence, hence the goal should have been disallowed.
This situation is also mentioned in IFAB Practical Guidelines for Match Officials:
An attacker in an offside position (A) is clearly obstructing the
goalkeeper’s line of vision. The player must be penalised for
preventing an opponent from playing or being able to play the ball.
Decision: Offside offence
Here is the freeze frame from another point of view, showing how Timo Werner obstructs Jarstein's (Norwegian goalkeeper) line of vision by positioning himself on the same line with Özil and Jarstein: