Hey there, so this is one thing i just noticed while playtesting version 1.5.1:

I remember from the earlier versions of this forge port that vanilla end biomes had ambient sounds playing while you were in said biomes, just like all the new biomes added by this mod which do have ambient sounds. Strangely enough these ambient sounds no longer play when you're in vanilla end biomes.

I even triple checked it. Tried mod version 1.1.0 and 1.2.0 in my 150 mods modpack, got no ambient sounds. Then i tried it with only BetterEnd mod version 1.1.0 & 1.2.0 and nothing else installed, and the vanilla end biomes were still silent. Then i checked if maybe the forge version could be the cause. Nope, both the recommended version and latest version for MC 1.16.4 (So Forge 35.1.4 and 35.1.37 respectively) don't play these vanilla end biome ambient sounds either.

The weird thing is, i remember exactly what this ambient noise sounded like and i swear these were in older versions. I looked into the mod.jar file to see if the file is even there, but i haven't found it unfortunately. Not in version 1.5.1 and not in any of the older versions jar files. I'm also 100% sure this whole thing is

Am i really just misremembering this or is this really a bug that has never been noticed? If it is a bug what could the cause be if it isn't other mods and different forge versions? I haven't tested it on MC 1.16.5 yet but i assume there won't be any difference.

I don't recall BetterEnd ever adding ambient sound to vanilla biomes, you are probably misremembering...or just made confusion with another mod, perhaps?

Ah i think i now know which mod that was! It must be Charmonium! Thank you for confirming that it wasn't in BetterEnd. I totally forgot i had Charmonium in it, because for unknown reasons that mod no longer works in my modpack.

I feel stupid now for not realising it sooner. Oh well, now i know at least. xD
Feel free to close this issue.