Using the Create mod and EMI with Forge in 1.20.1, the potion filling using the spout are not displayed.
There is one filling recipe for each type of potion (normal, splash and lingering) using water and giving a water bottle, splash water bottle or lingering water bottle, but no other potion is displayed in the filling catergory.
JEI shows these filling recipes without a problem when used without EMI.
JEI is also installed.

Interestingly, they do appear when checking the uses for the Mixer item, they just don’t appear when searching for the potions. I assume that’s because the potion liquids themselves don’t appear in EMI, only potions in bottles and tipped arrows