Question, what exactly is megasophagus and why is it bad? My best guess is that esophagus too big but I don't know why this would be so detrimental to kittens, nor why it would happen so much
The esophagus is supposed to be strong and muscular and stay closed when not swallowing and it's meant to actively push food into the stomach and keep it from coming back up if you tilt your torso down.
But if it's weak and flabby, it just flops open and can't push down anything so food collects in the esophagus unless gravity takes over. And in cats, the esophagus is parallel to the floor for much of its length so food will collect and just... sit there until the cat tilts in either direction. And if the head end goes down first and the cat breathes in while the food is coming back up, they can aspirate the food. Aspiration pneumonia is very very bad.
Most animals with megaesophagus end up with aspiration pneumonia at some point in time. You can train dogs to sit in these upright chair things when eating to help reduce the risk, but that's harder with a cat. It requires extensive maintenance and most of them still won't live a normal lifespan.
It's actually not particularly common. We see maybe 3 to 5 cases a year, across a couple thousand kittens coming in.
