In a nutshell, I'll explain what i did even though it doesnt actually mean anything. I did some mining, went above ground, then fished after emptying my inventory into a chest.
I exit the world using the Save and exit button, and then reopen it sometime later, though I had noticed my game had been closed, as in crashed. (RAM and storage shouldn't have been an issue. Also I was out of the room when it happened).
I decide to go back on to my world (if it matters, its an old style world), and I find myself with blocks ive recently placed missing, but my inventory the same.

So basically, everything reset except for my inventory. World loaded up the last save (prior to the exit of the world), mobs I had recently captured disappeared, and chests had reverted to the most recent save. Once again, everything reverted except for my inventory.

My world has no addons running, though I do have the old style minecraft resource pack on. I can't think of anything else that could be a reason of causing it to crash. The world is survival, as as mentioned before, neither Storage nor RAM should have affected it.

Also as far as i know, this has happened before to this world, and i know once for another on my IOS Ipad, though i can't remember if the world had crashed. Also forgive me if there is someone else who had reported this, I tried searching but nothing specifically discussed this.

Thanks for taking the time to go over this.

I'll upload the world, I named the folder to MCBug.mcworld (Not the actual world name..., once again, tmi)