Friend of mine relogged with a ruined Assault Vest (Smersh vest) with grenades and the Utility bag (Smersh bag) attached. On log in, he received the items were dropped notification indicating he lacked inventory slots and upon investigating found all items attached to his vest were gone. Not dropped, but deleted entirely from what we could tell. I will note this was also while swapping server, and so the player sat in queue and relocated across map.

My understanding is the ruined vest was checked on log in to see if it had a valid inventory, and found that a ruined vest should not allow attachments, so either they were dropped where the player originally logged out and then the player was relocated, or the items were deleted entirely.

Interestingly I've not seen this happen with ruined plate carriers but perhaps is a unique case, since the smersh bag is technically a clothing_base item, unlike pouch's being container_base. Interesting too is that it not only deleted the bag but all grenades attached too, which again doesn't happen with plate carriers to my knowledge?