I don’t think it will ruin your work data, should be other problem in krita.
Which krita version (number) are you using?
Could you show the full screenshot with the canvas get blurry?
Does it help if you clear Krita’s data (in Android settnig > app), it will clear all krita’s config and resource, as a result resetting all krita setting. So make sure you have some backup.
(Also backup your artwork, I don’t know if “clear data” will kill other data krita create or not)
(Don’t know if it is the same problem as this topic Every drawing became blurry , might still need to find the root cause of this issue 
)