Sincerely apologize if this is a repeat. I search multiple key words and couldn't find this issue reported...

Expectation is that parts of my world that I have already loaded and explored will stay the same unless altered by my own mining or building.

This newest update (while it has fixed the y levels and I'm stoked for that) has caused DRAMATIC changes to my exisiting biomes... I'll attach photos and I have a video also. When I say areas I've mapped already I mean for example the Jungle my world spawned me into, now as I've traveled back through it has a huge snow covered mountain that was never there before.... and I watched my map reload to add its presence...

Recreate this issue by loading a world with map loaded pre beta 1.17.30.23

If I might make a suggestion regarding this new biome edges transition (I'm assuming that is what this bug is involved with) perhaps my jungles could stop spawning next to frozen oceans and tundra since their temperatures are so vastly different? Separate issue I know but slight peeve of mine.