Hello!

Since the last update, I have in every biome from the overworld Nether ambiant sounds, which sounds really creepy.
I tried removing the mod and it indeed stops these ambiant sounds.

Here is my list of mods:
https://pastebin.com/2frpPRbR

Can you use the command /ambient-debug and send me a screenshot of it during it issue?

Yep, here it is:

Any resourcepack installed which could change AmbientSounds?

Yes I have a ressource pack but it doesn't change the base ambiant sounds and only adds a few more, I used the default sounds.json and engine.json and only added the sounds I wanted.

That is the problem, changes have been made to the engine so you should include these as well.