I have a strange feeling that the mineshaft isn't meant to look like this...

Also spawned both floating underwater and clipping into the better ocean monuments.

I'm using both terralith and tectonic, so it may have an issue with the floating part, but I have no clue what may have caused the copper bulbs and split iron doors. I checked and this is counted as a "lush cave."

My modlist at the time

cosmeticarmorreworked-1.21.1-v1-neoforge.jar
CreativeCore
Fzzy Config
Clumps
Forgified Fabric API
Dynamic Lights
Sophisticated Backpacks Create Integration
EMI: Create Schematics
Create: Dragons Plus
Terralith
TxniLib
Additional Entity Attributes
Cloth Config API
Create Slice & Dice
Tectonic
Elytra Trims
Sodium
Epic Knights: Shields Armor and Weapons
Almanac
Music Notification
Immersive Aircraft
ImmediatelyFast
Ars Unification
YUNG's Better End Island
Immersive Portals for (Neo)Forge
Ars Polymorphia
Sophisticated Backpacks
Wakes Reforged
Elytra Slot
Sound Physics Remastered
Geckolib
Mouse Tweaks
Fantasy Races
YUNG's Extras
Cultural Delights
YetAnotherConfigLib (YACL)
Ars Nouveau's Flavors & Delight
EMIffect
AstikorCarts Redux
Lithium
YUNG's Cave Biomes
Immersive Melodies
Chef's Delight - Farmer's Delight Villagers
oωo (owo-lib)
Brewin' And Chewin'
Dynamic FPS
EMI
Iris Shaders
Visuality: Reforged
Elytra Trims Extensions
Forgematica
[ETF] Entity Texture Features
Farmer's Delight
Create: Enchantment Industry
YUNG's Better Jungle Temples
Bookshelf
Sophisticated Core
TerraBlender
TerraBlenderFix
Essential Mod
Particle Rain
Create & FD Dough
Create Man of Many Planes
Cool Rain
Connector Extras
Lionfish-API
Astrocraft
FerriteCore
Particular ✨ Reforged
Enchantment Descriptions
Ars Nouveau
YUNG's Better Mineshafts
YUNG's Better Witch Huts
YUNG's Better Strongholds
Create: Wrencheable Planes
EMI Enchanting
Simple Discord RPC
YUNG's Better Nether Fortresses
YUNG's Bridges
EMI Addon: Extra Mod Integrations
Distraction Free Recipes (EMI / REI / JEI)
Create: Let The Adventure Begin
Horse Expert
YUNG's API
CraterLib
Curios API
Create Crafts & Additions
Moonlight Lib
YUNG's Better Dungeons
EMI professions (EMIP)
Man of Many Planes
Create: Integrated Farming
Dungeons and Taverns
3D Skin Layers
Let Me Despawn
Sinytra Connector
My Nether's Delight
Create: Design n' Decor
Lithostitched
Better Combat
Straw Statues
EMI Loot
Kotlin for Forge
playerAnimator
EMI Ores
Aquatic Creepers
Prickle
Create: Aquatic Ambitions
Onion Onion
Entity Culling
YUNG's Better Ocean Monuments
Create: Copycats+
AppleSkin
AmbientSounds
Create: Central Kitchen
Just Enough Items
Not Enough Animations
Map Atlases [Forge]
Architectury API
MaFgLib
Create
Immersive Paintings
Better Clouds
Caelus API
Horseman
L_Ender's Cataclysm
Dungeons and Taverns Ancient City Overhaul
Create: Misc and Things
Attract to Sound ([NEO]Forge/Fabric): Sound & Stealth.
[EMF] Entity Model Features
Puzzles Lib
YUNG's Better Desert Temples
Polymorph
Epic Knights: Addon