This may be mobile specific, I've not been on the PC for a while, but whenever you enter living death/metamorphosis, you're unable to open certain interfaces what so ever in mobile. This becomes tedious whenever you are doing AFK combat like certain slayer or bossing.
Surprisingly often I find myself fiddling about in the settings or want to check out achievements during these activities, and having to wait out the transformation timer to open settings or achievement lists, community page, or for changing other stuff you otherwise can at any point in combat is just strange in general.
I'm not sure why metamorphosis/living death prevent you from opening these interfaces but it would be lovely if this restriction was lifted, or to at least have it properly explained as to why they need to prevent opening interfaces.