When you switch to a newer version, sometimes the seeds reset depending on the features, that means if you were in a jungle in your world and you switched to 1.14 Beta, the biomes, structure generation, etc. may reset. So the blocks, player data, and entities, may stay the same unless they were deleted or modified, but instead of the game thinking it's a jungle, it now thinks it's a cold biome, such as a Tundra, and that's what is causing it to snow. If you go away from the chunks that were loaded in the version you created the world, then you may see a huge chunk border wall.
Mudathir abdelrahim
When you switch to a newer version, sometimes the seeds reset depending on the features, that means if you were in a jungle in your world and you switched to 1.14 Beta, the biomes, structure generation, etc. may reset. So the blocks, player data, and entities, may stay the same unless they were deleted or modified, but instead of the game thinking it's a jungle, it now thinks it's a cold biome, such as a Tundra, and that's what is causing it to snow. If you go away from the chunks that were loaded in the version you created the world, then you may see a huge chunk border wall.