While this primarily deals with the 737 MAX, it has an impact on many other flights due to shuffling aircraft.
I dumped my AA tickets after they changed for the second time in a month after purchase and NO notification. Got air on Delta at a lower price and extended the trip. Sadly, the same tickets on Delta have over doubled to $1600+.
Ugh, have my first trip booked for July 1st on AA out of Philly. It was changed once to a slightly earlier departure from Philly (fine with that). I was notified by email and in my AA app. Hope nothing else changes as we are due to leave soon!!!