OP has intentionally taken this screenshot from a few frames after the shot is taken because the player is moving across, probably still not really interfering but this screenshot isn’t what VAR would be looking at

He’s still in his line of sight though? Swear these have been disallowed before

Yet Maguire gets flagged offside for being nowhere near the ball as well

Well that settles this particularly stupid debate

One other point would be that by being in that offside position, Onana shades to that side of the goal in case the offside player were to receive a pass. If that player is NOT there, is Onana more central in the goal? Subjective decisions.