Hello,
So I just updated from v2.3.5a to v2.4.1 forge and it has messed up the terrain gen. If it was meant to happen, it would have been nice to have a disclaimer in changelogs.

Oh yikes, that wasn't supposed to happen

Can't replicate, just tested loading a v2.3.5 world on v2.4.1 and nothing changed other than slight adjustments in swamps. Can you provide a mod list?

Hello, sure I can. https://www.curseforge.com/minecraft/modpacks/pokeasub Here is the modpack that I use. The most recent version has v2.3.5, but the one before has v.2.4.1, as I needed to downgrade, so I don't get more weird chunks. I tested if any of the other mods that I changed in the update did something, but no. I am guessing one of the mods is now incompatible with the latest version of Tectonic.

I believe the issue here is the modpack using both Lithosphere and Tectonic. Both mods are complete overhauls of terrain shaping and shouldn't be used with one another. What I assume happened is that Tectonic 2.4 had some backend changes that altered how Lithosphere and Tectonic interact, causing chunk borders.

There's not really a good way to fix that other than staying on v2.3.5.

Gotcha, thanks for help <3