The bug

The filter will not filter out the specified path in the namespaces that are not "minecraft"

The attachment is a datapack to verify this behavior. It contains a pack.mcmeta that filters out recipes from any namespace and a custom namespace with a recipe and an advancement in it.

How to reproduce

1. Download the datapack attached and install it to a world
2. Enter the world
3. Place down a crafting table, go into its GUI and click open the knowledge book
4. The custom recipe that is supposed to be filtered out is shown