Loading a pre-1.2 update world in 1.16 or newer causes the user to get a peristent experimental world error even though said world doesn't use experimental features.

How to reproduce:

1) Create a world in any version b1.3-1.1

2) Save and quit game

3) attempt to load said world in 1.16.x / 1.17.x

4) Wait for said world to finish converting

5) You should get the experimental world settings screen. It doesn't go away after first boot.

I have a survival world on release 1.1 that I've been wanting to update to a modern version and this issue is basically forcing me to use a mod that removes said experimental world screen so I don't have to look at it each time.

A potential temporary fix that I haven't tried is loading said world in 1.15.2 first and reopening in 1.17.