The "Historical" option is actually destroying everything you built

Hello!

Today I tried to make an EXP farm, yet it didn't work on the snapshot 20w19a. but that's not the point;

I later on tried to use version 1.15.2  to run my world and that deleted everything I had on that world (AKA Like whole days of progress; I was almost ready to fight the Ender Dragon, which is basically as far as I got ever) I thought to go back to the Snapshot and it'll fix, yet it haven't.

So I basically lost everything I built except for the tools / items I had on me.

This ruined my experience and could ruin experiences of many other people.