Died suffocating in wall while mining.

As long as the system allows to select spanish I thought i could write my problem in spanish.  
I was playing minecraft in its phone version, i was chopping stones at layer -59 (I say it because there was nothing below) and suddently the screen flashes and appeared the message saying that I was dead. The system said that i was suffocated by a wall, but i could not see anytihng, just screen flashes. I went to the place I supposedly dead, but there was nothing more than the tunnel i’ve done before (no holes at the top nor bottom). I’ve lost everything I had. 

Also, I don’t know if this has anything to do with it, but when i run the game, the first steps before I select My World, the game really goes very slow. The phone where i have the game is new (iphone 15 pro) so I don’t think it is for that. I will try ro leave you a recording of that.