A malformed tag in a data pack will prevent all data tags from loading

If any data pack has a malformed tag (references a nonexisting item or tag, references itself, or has a malformed ID), the data pack loading system will encounter a cascading failure that prevents any tag from loading. The most visible result of this is that the leaves on natural trees will begin to despawn, as they can no longer tell that they are connected to logs, since the minecraft:logs tag never got loaded. The attached data pack will cause this issue.