I still haven't seen/read any explanation of why Lacazette's goal was ruled out? If he was called offside because of his positioning on the initial ball over the top --- yeah, he probably was, but then the whistle was reeeeeally late for that. Immediately thereafter, the defender played the ball intentionally back toward his keeper, at that point Lacazette's is not offside. And if the call was for that, it was just blatantly wrong and would get a high school ref in trouble with their assessor.
One analysis I read argued that the Ref's Assistant waited to raise the flag for offside until observing the defender was "influenced" by Laca playing from an offside position in the "first stage" after the flick from Auba. It makes a little more sense with that interpretation, but as you mentioned, that's not how the referees are supposed to call it. If Laca is interfering/involved in the play, it should be an immediate flag for offside and not waiting to see what the defender does. I still think it was a bad call, but at least we won. Hopefully these marginal calls start to return for our favor.