Merch restock?

Honestly silly of me, but I never knew buying their merch outside of concerts was an option until today despite being a fan for 5 years :,)
I noticed literally everything but one shirt was sold out, but it did give me an option to be notified via email when an item is restocked (specifically the Dalmatian hoodie).
Main point; has merch been sold out like this for a while, and when was the last time someone got a restock notification? Trying to figure out if this is a hopeless dream lol

Note: unsure if this is better for merch or question flair, sorry mods