Backpack empty, Forge, 1.19.2 about sophisticatedbackpacks HOT 1 CLOSED

My guess is that the SimpleShops are selling backpack with preset UUID which is going to be the same for every backpack bought that way. Which then means that such backpack will automatically get deduplicated using logic that's in the SB code, what that does is go through backpacks of all players online at the moment and collect UUIDs, as soon as it hits a backpack with UUID that it has already encountered it sets a new UUID for that backpack which effectively clears its contents.
So what I think happened there is that another player bought the backpack, the logic encountered their backpack first and then found yours and marked with new UUID making it empty. The other player would still have access to all the items that were in the backpack before.
Proper fix for this would be having the simpleshops sell backpack without uuid so that this won't happen again. I am closing this now but In case this is not what's happening for you and you have steps to recreate the issue (that I can use to recreate the issue for myself) let me know

from sophisticatedbackpacks.