Somebody please explain the DIET soda shortage?

I'm sure many are aware, it is hard to buy some flavors of diet soda in the supermarkets since all the pandemic restrictions started kicking in.  Major soft drink manufacturers are on the record saying the cause of the shortage is TWO things:

1)  They are running out of aluminum cans to package the diet soda in.  (Ok, that is logical)

2)  They are running out of artificial sweeteners to make the diet soda.  (That does not compute!)

For number 1, a shortage of aluminum cans would lead to a shortage of all flavors of soda in the grocery stores.  But I'm not going to question it.  It makes sense that if more people are staying home, then more soda is sold in aluminum cans.

For number 2...

Imagine you go out to eat in a restaurant.  It could be fast food or casual.  You order a diet soda.  The diet soda will be 18-32 ounces (probably).  And you might get refills, as well.  ***** OR *****

You do NOT go out to eat in a restaurant.  You stay home to eat.  You choose to drink diet soda with your home meal.  Maybe you drink a can.  Or you drink TWO cans of diet soda.  Or you drink a bottle of diet soda.  Or part of a large bottle of diet soda.  Whatever.  Are you drinking MORE diet soda????????????????????

In my mind, it makes sense that if you go out to eat, and order a diet soda....then you are probably drinking MORE diet soda in a restaurant than you would at home.  How is it that people eating at home are supposedly causing a shortage of artificial sweetener?