Over a 50 year period I've visited Reims and Epernay many times and visited many of the "big" champagne producers, at the end of the tour you get to sample (for a fee) some nice champagne--I'm certain none of these had apple under/over tones.
Yes, what I was served in flight was (as noted in #8 ) Gardet.
What is most annoying (to me) is that AA in their Flagship lounge and DL in the SC serves some nice champagne, yet on the plane they serve stuff of lesser quality.
Given that Dom has notes of guava and grapefruit, I truly don’t understand why you think apple notes indicate lesser quality.