When I was farming Wither Skeletons earlier my PC suddenly started lagging (The lag wasn't from Minecraft) and I ended up getting killed by the Skeletons, then out of nowhere my PC crashed and switched off while I was in the death screen

Once I'd restarted and booted Minecraft backup I logged into my world and I was still alive but lost a little bit of progress, I just thought I got lucky and carried on farming. However I soon found the place where'd I'd previously died and all my inventory was spread across the ground. So all my items had been duplicated

Later on I did some testing in creative world to see if I could reproduce the issue and did

1. Open task manger on Windows
2. Load up world and fill your inventory with random stuff
3. Wait about 10 minutes
   1. I don't really know how it works but you need to wait for Minecraft to 'autosave' your progress
4. Die
5. Don't click respawn
6. In task manager kill the Minecraft process
7. Reload Minecraft
8. Log back into your world and you'll have lost some progress but you'll have still have all you items as well as them being dropped where you died

Not too sure how you'd fix this as I think it's related to how often Minecraft is committing progress to storage and you might introduce a load of lag if you increase that. Although I thought it was interesting so figured I'd let you guys know

It might be somewhat related to MC-145022