It's not that easy to calculate as "munitions" can be anything from artillery shells to ballistic missiles.
If we assume it's mostly/all artillery shells, it's roughly one month of production. Russia currently produces 250.000 units of artillery shells per month if everything goes right. Russia uses roughly 10.000 of them per day, so it would be almost one months worth of combat.
If the stockpile contained more of glide bombs and ballistic missiles, the damage is even worse because they are significantly more expensive to produce.
Honestly, I don't see a problem with this.
Some people are just really shit with emotions. Me included. I just got no clue what to say in certain situations. I know that what they do is not an issue, but I just don't know how to tell them properly.
Using AI for this is a fair use-case - you want the person to not feel bad, and if AI can give you a better response than you yourself could, why not.