Nowdays, I want to find some blocks like oak wall.

And i finally find it from https://www.mcmod.cn/item/177551.html

However, I can't find it in mincraft nor this repo.

Is there some bug?

Oak Walls do not exist in the 1.14+ versions. You can find a full list of the current features at https://quark.vazkii.net

Furthermore, that website is not affiliated with us. If you want to download the mod, the right place is in the website I just linked.