Vests are a type of equipment in Battlegrounds. They provide basic protection and an increase in carrying capacity. Body armor will last until fully destroyed by gunfire or other types of damage and will block the full damage even if it has only 1 point of armor left. It is useful to pick up a vest no matter what level it is as it provides protection against instant-kills with body shots, most of the time.
Update #41 (Season 7 - Update 7.2)
Vests not only provided armor but also provided additional inventory space. However, it felt pretty bad to immediately lose that space when your vest was destroyed in combat. Your survivability also drastically decreased once your vest was destroyed. leaving you extremely vulnerable until you found a new one. With this change, ‘destroyed’ vests will no longer disappear, and neither will your inventory space.
In addition, vests will continue to provide 20% protection and slight aim punch reduction once destroyed. The base protection level of the destroyed vest is the same no matter the type of vest you’re wearing. This should mean more competitive engagements, even if the situation doesn’t allow for the looting of a new vest.