No word on what the problem is. https://abcnews.go.com/US/american-airlines-requests-ground-stop-flights-faa/story?id=117078840 It has to be some computer system for them to do this.
I am reminded today I am more likely to fly with Santa and magical reindeer than to fly on a modern jet. Think about the fact that flying sleigh travel is engineered to put you in the poop path which is light years beyond what boing has made of air travel