The only reason I even believe the mandela effect is real is because my body has changed in significant ways.

Literally everything else could potentially be memory issues, perception issues, AI trickery etc. Except our bodies themselves have changed.

Moved/enlarged liver- to deal with a more toxic environment.

Kidneys under the ribs now- protection of vital organs.

Covered eye sockets and more skull sutures- more protection from a harsh environment, maybe from increased earthquakes.

Those are the big ones I can think of off the top of my head right now.

And there are Mandela effects I've noticed personally in my own body- The tops of my thigh bones are bigger, and wider now. My knuckles are all noticably bigger as well. The reason that made me think of earthquakes was because I was trying to reason out why my lower hip area would be wider and I think it might be to increase balance ability, with a slightly lower center of gravity

All together I think these changes point to needing a stronger, more robust body and organ system for an increasingly harsh environment. These are just my crazy thoughts.