The armor don't drops after the players death, or drops, but with random durability. That looks like zombie/skeleton armor drop chance expends for players, because when you dying by hunger, fall or other thing, and you don't attcked by other player/mob, armor don't drops, but when you dying because damaged by other player(or you can kill yourself with potions with instant damage effect) or by mob, armor have chance be dropped.
I'm tested this on 3 different worlds, all difficults (without peaceful, because there don't spawning agressive mobs), I'm restarting the game, this bug don't disappeared.
Model: Redmi 4x
Manufacturer: Xiaomi
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-35479.
Please add a vote and any new information to the main ticket, which will be updated accordingly.
If you have not, you might like to make use of the search feature before making a new ticket, as it's likely that the issue has been reported already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Feedback – 📖 Game Wiki