Wilder Wild's biomes appear to be generating almost perfectly on chunk borders, as seen in the screenshots - this is not an issue with vanilla biome boundaries, only WW ones. Additionally, there also appears to be the ugly terrablender micro-biome gen happening (which is not among my mods - I avoid it for this exact reason)

• Minecraft 1.21.1 fabric, WW 4.0 (+TT 1.1 if that matters) -

I do have Biolith (for NewWorld) and Lithostitched (for Tectonic), so I am unsure if there is a strange compatibility thing with those?
I have also not seen this behavior when I was running 1.21.1 Neoforge (nearly identical modlist, but obv without WW) so unless the fabric versions of Biolith or Lithostitched behave oddly it likely has to be WW.

The border of NewWorld's wooded meadow is blended, but right next to that is a bunch of super wack WW rainforest gen (up to nearly 300y!)

logs:
latest.log

Biolith is at fault, even in their own mod they appear to break the normal multi-noise gen. Biolith integration is planned to utilise non-multi-noise in order to mitigate their issue, such as using sub-biomes with parameters instead of the vanilla hypercube used in all biomes normally

TLDR this will be fixed in 4.0.1, and hopefully fixed even better if Biolith is able to fix their multi-noise problems

In my testing i have not seen this happen. Likely an issue with WW lacking support for those biome placement libraries.

Are you able to record a video of flying between the biome borders, with f3 open?
In multiple spots preferably

This way I can see whether the placement conditions are changing, if not then something is in fact wrong

Can confirm this is an issue. WWs way of adding biomes seems to break with Biolith

Same seed, same location

I will be investigating biolith integration in order to hopefully resolve this issue

Solution: rebel makes biolith compat because I don’t have motivation for it

do you still need the video rebel?

I don't think so... but this is still very strange. Biolith definitely causes the problem, however it appears worse with my modpack instance than just biolith/newworld + wilder wild

Same effect but amplified, idk why

crazy how many biome libraries keep doing these weird things (I vaguely recall lithostitched when it first existed was WACK, terrablender just has sucked for a long time, and somehow I feel like there was a third one many years back but idk lmao)

Yep. Should have Biolith integration done today provided Luna accepts the PR

just a note, there aren't any improvements to this wacky gen with WW 4.0.1 so hopefully the integration works out well

4.0.1 doesn’t include Biolith integration, otherwise it would be included in the changelog. I wanted to get a release out to resolve a server issue on 1.21.4.

yeah I just threw that out there regarding rebel's previous comment

Biolith integration is complete and will be included in 4.0.2