This is the bug tracker for Java edition, the bug tracker for bedrock edition is here - https://bugs.mojang.com/projects/MCPE/issues/MCPE-91519?filter=allopenissues
I did not open the same world, I created a new one and left it with the default name. I should have clarified, but I was not asking for downgrading to be supported, just for a warning or something to come up saying that you are creating a world with a name that already exists and that this will delete the other save.
I have edited options.txt but never anything on the render distance line, I have played that world on multiple versions (only from 1.16 to 1.16.4 though). However, the world has been on 1.16.4 ever since it was released without any issues. Same goes with mods: I use mods like litematica and minihud along with sodium, lithium and phosphor but have used them for a while without any issues.