@TavIsMyMain

The issue can present in two cases. Either you unalive an enemy, and their hp total is >0 but the status shows dead when you mouse over it. Or, it's an already dead individual that spawns into the game when you enter a certain area of the game. In the former, if you don't catch it soon enough, aye it will disappear and leave a pouch, but the game caches the hp total so at that point there's no coming back from it.

In the latter, those NPCs remain longer. If the issue you have is from the former category, and PS5 has deleted the functional save prior to that incident, you are correct a patch or restart will be required. However if it's the latter, you'd have to track down that corpse but it won't disappear at least. The Foundry, Blushing Mermaid, Murder Tribunal, and House of Grief appear to be where this occurs the most based on reports I've seen here and on Reddit about this issue. But in truth it really can be anywhere.

As someone who banged his head against the wall on this issue, I feel your pain and am sorry you're having to go through it. If you're brave and want to risk potentially having to restart from an even later point, you can try those areas you haven't yet. Larian has not acknowledged this bug or several other game breaking/quest breaking bugs publicly and the tech response I got on this issue was that it's mod related (I don't use mods), so I'm not sure how much hope there is for that alternative.