The edits applied to Relics Config (Relics 0.8.0.7 - forge) does not take effect, and after starting the game, new config files are created inside the Relics folder, duplicating files and making the old ones stay in a folder inside the new one.

There is nothing referenced in logs, nor crashes.

Playing in a modpack:
[Let's Do] API
Radiant Gear
[Let's Do] Furniture
Heartstone
Xaero's World Map
CTOV - Domesticated Innovation Compat
Bad Horse Fix
Not Enough Animations
playerAnimator
Global Packs
Spice of Life: Apple Pie Edition
ars_artillery-1.1.7-forge-1.20.1.jar
Fresh Animations
More Mob Variants
Polymorph
CERBON's API
Shut Up GL Error
AdoraBuild: Structures
Complementary Shaders - Reimagined
The Bumblezone - NeoForge/Forge
Mouse Tweaks
Lootr
Nature's Compass
Elenai Dodge 2
[ETF] Entity Texture Features
Easy Magic
[Let's Do] BloomingNature
Iron's Spells 'n Spellbooks
Ocean's Delight
ars_nouveau-1.20.1-4.12.4-all.jar
TerraBlender
Dungeon Now Loading
Iris/Oculus & GeckoLib Compat
YUNG's Better Witch Huts
EnlightenedBlockEntities
CoroUtil
Embeddium++
GraveStone Mod
Icarus
ComplementaryReimagined_r5.2.2.zip.txt
Arcanist's Equipage
Horse Expert
EMI
Realistic Bees
Better Days
Structure Gel API
Building Wands
Citadel
TrashSlot
Dynamic Crosshair
Exposure
Starlight (Forge)
CERBON's Better Beacons
End Remastered
Memory Leak Fix
Puzzles Lib
Plushie Buddies
3D Skin Layers
AppleSkin
[EMF] Entity Model Features
Jade 🔍
Infinite Abyss
YUNG's API
Blur Forge (Unofficial)
CorgiLib
YUNG's Better Nether Fortresses
ToadLib
Better Advancements
AeroBlender
Magnum Torch
Amendments
Oculus
MonoLib
Item Highlighter
Majrusz's Progressive Difficulty
TerraBlenderFix
1.21 update | Tricky Trials
[Let's Do] Bakery - Farm&Charm Compat
Resourceful Lib
YUNG's Better Desert Temples
No Chat Reports
Easy Anvils
Immersive Aircraft
Deeper and Darker
FPS Reducer
Lithostitched
Cloth Config API
Fzzy Config
Continents_1.20.x_v1.1.5.jar
Dynamic Music Updated
Vegan Delight
Enlightend
Tiny Item Animations
ImmediatelyFast
I Want That Back
tetra
Rainbow Reef
CERBON's Better Totem of Undying
Alternate Current
Smooth Boot (Reloaded)
Terralith
Passive Shield
Iron's RPG Tweaks
ToroHealth Damage Indicators (Updated)
YUNG's Better Ocean Monuments
Clumps
Better Beds Reforged
ServerCore
Reforged (formerly Tiered)
Better Biome Reblend
Supplementaries
Incendium
Searchables
Geckolib
KleeSlabs
Rebind Narrator
Delightful
Aether Villages
Zombie Awareness
Jumpy Boats
cat_jam
Overflowing Bars
YUNG's Better Dungeons
[Let's Do] NetherVinery
YUNG's Better End Island
[Let's Do] Meadow
MidnightLib
Tetratic Combat Expanded
Spawn Animations
Better Ping Display [Forge]
[Let's Do Addon] Corn Expansion
BadOptimizations
Chipped
Relics
ElevatorMod
CreativeCore
Model Gap Fix
Naturalist
Hey Berry! SHUT UP
FerriteCore
The Aether: Redux
Water Walking Fix (Forge)
Effect Descriptions
PlayerRevive
Enderman Overhaul
Snow! Real Magic! ⛄
Xaero's Minimap & World Map - Waystones Compatibility
Kambrik
Feathers
Global Server Config
Guard Villagers
Ars Additions
Pop!
Dismount Entity
Visual Workbench
Shiny Horses - Enchantable Horse Armor
Ping Wheel
ChoiceTheorem's Overhauled Village
Better Archeology
Not Enough Crashes
Out Of Sight
Too Fast
AttributeFix
[Let's Do] Beachparty
RestApi
Max Health Fix
Creeper Overhaul
Echo Chest
OctoLib
Simply Swords
Friends & Foes (Forge/NeoForge)
Just Enough Items
The Aether
Cubic Sun & Moon
Collective
Tetra's Delight
Nether's Delight
Curious Armor Stands
Farmer's Delight
The Lost Castle
[Let's Do] HerbalBrews
Philips Ruins
True Ending: Ender Dragon Overhaul
Regions Unexplored
Default Options
Omega Mute
Ars Artifice
SuperMartijn642's Config Lib
[Let's Do] Candlelight - Farm&Charm compat
ars_elemental-1.20.1-0.6.5.0.1.jar
Spyglass Improvements
Better Safe Bed
L_Ender's Cataclysm
Enchantment Descriptions
Tool Stats
AstikorCarts Redux
Iceberg
Fast Paintings
No Telemetry
Cull Less Leaves Reforged
Embeddium
Better Than Mending
MmmMmmMmmMmm
Particle Core
Villager Transportation
ChickensShed
Leave My Bars Alone
Architectury API
Better Combat
Noisium
Overweight Farming
Domestication Innovation
BetterF3
Enhanced Celestials
YUNG's Better Jungle Temples
GeOre Nouveau
Sparse Structures Reforged
Zeta
[Let's Do] Brewery - Farm&Charm Compat
Iron Chests: Restocked
Not Enough Recipe Book [NERB]
HT's TreeChop
[Let's Do Addon] EMI Compat
GeOre
Bountiful
More Mob Variants x Fresh Animations
bad packets
Bookshelf
Entity Culling
UnionLib
Packet Fixer
Liberty's Villagers
MaFgLib
letsdo-addon-compat-forge-latest.jar
Kiwi 🥝
Villager Names
More MobGriefing Options
Block Swap
Quark Programmer Art.zip
Friends&Foes - Beekeeper Hut (Forge/NeoForge)
[Let's Do] Vinery
Call of Yucatán
Lionfish-API
Deeper Oceans
Horseman
Tide
aleki's Nifty Ships
Do a Barrel Roll
Mobtimizations - Entity Performance Fixes
Common Network
Aether: Lost Content Addon
CTOV - Iron's Spells 'n Spellbooks compat
Nyf's Spiders
Shield Overhaul
Critters and Companions
AI Improvements
Traveler's Backpack
ThreatenGL
Controlling
Athena
Dragon Mounts: Legacy
Moonlight Lib
Quark
Saturn
Kotlin for Forge
Make Bubbles Pop
Medieval Buildings [End Edition]
Artifacts
[Let's Do] Farm & Charm
First-person Model
Default World Type
Curios API
Let Me Despawn
Water Balloon
Forge Config Screens
Ribbits
Patchouli
NetherPortalFix
YUNG's Better Strongholds
CTOV - Friends and Foes Compat
Xaero's Map Server Utils
Better Third Person
Storage Drawers
Fish No Stuck
End's Delight
Waystones
Majrusz's Accessories
Rain should extinguish campfires
Caelus API
mutil
Fast IP Ping
Balm
Bosses of Mass Destruction Forge
libIPN
Resourceful Config
Majrusz Library

The issue has been solved and was user error