As a result of the death of a character, you only lose their inventory. There is a chance that the corpse will remain at the same place, and that resources will be returned, however, a lot of things can happen along the way. Your character may be killed a second time, the location may not be found if it was a time-limited event, or found, but with no corpse there (for example, if the character dies inside the basement, then, after leaving the zone, the basement disappears with the corpse in it). Therefore, resources in the game can be lost forever (full drop system).

Purchased items have the same characteristics as the ones found. Weapons and armor will break when they run out of durability, purchased resources can be accidentally deleted or recycled by you and, finally, lost forever after your survivor dies.

So, it is better to keep purchases in the inbox or on your own base, you should not hand the purchased object to a character without weapons, armor and a supply of healing items, it is always better to make sure that there are no enemies around if you open inventory or inbox (after all, the game does not put itself on pause) etc. Parsimony and vigilance are the best qualities in the post-apocalyptic world :)
If you lost things you bought due to some other reason, inform us and we will be happy to help!