To add on to game being unplayable. I have been trying to play a little in between phone getting super hot and have noticed that items are disappearing. Have lost an Ender chest, a shulker box and a bed since this update. One minute they are there and then I stop playing due to phone getting very hot. Come back to game and things are just gone. Really like playing game with my son, but current version has rendered game basically useless.
I have had the same situation. iPhone 11 Pro Max on the most recent iOS and I have a very light case, but I’ve also had the issue when I’ve taken the case off. Phone gets hot where it never did before and causes the phone to limit brightness. Also causes significant battery drain. Way more so than before the update to 1.16.20 I have no mod packs or data packs. Also not playing while charging my phone. Before the update this was never a concern, it only happened right after i downloaded 1.16.20. I have to most recent iPhone, if it cannot handle the game then I think something must be wrong.
After downloading the update I'm still experiencing my phone getting hot enough for it to automatically reduce brightness. Using an IR thermometer the back of my case-less iphone registered 111 F. It doesn't seem to get hot as quick as before the update, but it is still happening where it didn't happen before the update to 1.16.20. I am running no data packs or anything of that nature. All my settings are on default and I have a Iphone 11 Pro Max running the latest version of iOS.