Is this a Bug or i got Virus

I used cracked apk for a short bit cuz my friend installed it , then I eventually bought the minecraft app from play store but now every day at random times my minecraft is deleted , idk how but I am playing it like 30 min ago , i left my tablet and came back and its gone ... I reinstall and get my world and stuff back no need to login as well but how did it got deleted ??? I am playing on Android tablet if it helps :)