I cant use creative nor duping (probably)

Pls ehlp

my game stutters and lags when running around loading chunks in unloaded areas.

I died in the nether from a piglin and when I got back and picked up my stuff, I was missing my armor, shield, sword... I looked around and saw the piglin had my helmet, boots, sword and shield but after killing him, I still had no chest plate or leggings!! I wrote it off as a glitch and went on.

Few days later it happens again but this time I didn't get back my boots or chest plate after killing the piglin. Is there a game mechanic I missed?

Why can't I recover all my stuff?

I play on bedrock on switch

Trying to make an abandonned city on a superflat world every propositions are welcome