No Stacking Potions

This datapack made by AuraAcorn have many different features which my server members love but there's one that no one likes and is very glitchy , Stacking drinkable Potions to 16 
I tried to examine the datapack to see where the code for it was kept , but failed , now I mostly find what I want in datapacks but this datapack is just a huge web of features , here's the datapack , now I know this is not the correct use of this channel but I need help plz