Work-around in their twitter feed doesn’t work for me. I didn’t have the Xboxlive app, so I downloaded it to try it, it being 1. Force close Minecraft, 2. Sign out of Xbox live, 3 sign in to Xbox live, 4 start Minecraft. Didn’t work. I always signed into Xbox live via Minecraft menu, but because it freezes before that appears, there is no way to sign out as far as Minecraft is concerned.
I did a test in Win 10 single player and it has a sense of being fixed for that. I set up a blaze spawner, switched to hard survival, and engaged in some melee combat with them, suffering repeated fireball attacks, but no instant deaths. I then went and found a fortress, same result. Some time ago I did a similar test, and about 1 in 10 (not an exact number) of the fireball attacks would result in instant death. I've yet to try it in iOS PE single player, where before I had a similar result to Win 10 (about 1 in 10 fireball attacks resulted in instant death). Side note: For me, armor destruction during instant death was much rarer than the instant deaths themselves.
This previous post copied below worked for me to get it working in offline mode at least. You use the Files App on iOS to access the folder and file “Options” mentioned in the post.
Side benefits for me...!
Load speed huge increase
Rendering distance huge increase
Texture rendering bug I had for foliage and water fixed
Szilvási Ádám added a comment - Yesterday
There is a workaround on iOS. Delete the options file (after duplicating, so when services come back online, you just restore it) in Minecraft>games>com.mojang>minecraftpe folder. It will reset all options, including the XBox Live login, then the game will start up logged out and will be working fine.