It is a bit late now but wanted to document it here so it is not forgotten about. Nouns should be plural so this tag not being called coals was a typo. It isn't in neo side so no mismatch there. But it can't be fixed on Fabric's side without it being a breaking change in code unless a second coals tag is made, deprecate the singular one, and pull in the singular one into the plural one as an optional entry.

Hmm, why is this coals in NeoForge? Coal is uncountable.

I believe we decided that we still use the 's' even for uncountable nouns, since the tags collect different types of them, so it is sort of grammatically correct. Like you can have lots of fruit, but also lots of different fruits. You can have lots of coal, but also lots of different coals.

Hmm, why is this coals in NeoForge? Coal is uncountable.

What shnup said. It’s why the tag convention is fishes and meats because it’s easier and less likely to cause confusion on whether to have an s or not for a noun by going with thinking of the tags as different types of stuff which would then required the s. Thus all nouns should have s generally. If confused, add s.

The coal tag isn’t on neoforge side yet though at all. Might add it over there to match if I can find some neoforge mods with different coal types.

: thonk :
Coals is a Mc tag

https://github.com/misode/mcmeta/blob/data-json/data/minecraft/tags/items/coals.json

Now I’m curious, what was fabric’s motivation originally to have a coal tag under c instead of using mc’s?