Hello !
Sometimes, PVJ blocks cut double plants in half at the worldgen, this is an issue I've been seeing since 1.16.5 but as nobody is talking about it I'm starting to question myself

This is a large fern plant from minecraft vanilla, it happens with vanilla & modded plants, the block under it is a mossy_rocks block

Here is the complete modlist, you can also just download the modpack where this issue occur to get the full setup quickly : https://www.curseforge.com/minecraft/modpacks/minecraft-legendary-edition

modlist.txt

Thank you for your amazing work !

I think this happens in vanilla as well but much more rarely. Will look into this more

If it's of any help, this was fixed in the Snow Under Trees mod like so

Forgot about this - just released a quick fix for 1.20.1